Photoresist frame plating method for forming planarized...

Details Photoresist frame plating method for forming planarized... Photoresist frame plating method for forming planarized...

1996-04-17

2002-04-09

Hall, Carl E. (Department: 3729)

Metal working

Method of mechanical manufacture

Electrical device making

Reexamination Certificate

active

06367146

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to magnetoresistive heads used in magnetic recording.
BACKGROUND OF THE INVENTION
Dual-stripe magnetoresistive (“DSMR”) read-write heads are known in the art to have a number of advantages such as facilitating improved areal recording density.
FIG. 1
illustrates a read-write head comprising a slider
1
and a read-write element
2
mounted on the trailing side of a center rail
3
of slider
1
. Read-write element
2
is used to read data from and write data to a magnetic disk during use.
FIG. 2
a
illustrates in cross section read-write element
2
along lines A—A.
FIG. 2
b
illustrates in cross section read-write element
2
along lines B—B.
Referring to
FIG. 2
a,
read-write element
2
is formed on slider
1
, which is formed from Al
2
O
3
—TiC. An Al
2
O
3
insulating layer
12
, a bottom pole layer
14
(typically a NiFe alloy), an Al
2
O
3
insulating layer
16
, a first magnetoresistive stripe
18
(typically a NiFe alloy), a first pair of exchange layers
20
a,
20
b
and a first pair of contact layers
22
a,
22
b
are formed on the slider material. Contact layers
22
a,
22
b
are used to electrically contact magnetoresistive stripe
18
. Exchange layers
20
a,
20
b
are used to stabilize the domains of MR stripe
18
.
An Al
2
O
3
insulating layer
24
is formed on contact layers
22
a,
22
b.
A second magnetoresistive stripe
26
, a second pair of exchange layers
28
a,
28
b
and a second pair of contact layers
30
a,
30
b
are formed on Al
2
O
3
insulating layer
24
. Contact layers
30
a
and
30
b
are for electrically contacting magnetoresistive stripe
26
. Exchange layers
28
a
and
28
b
stabilize the domains of MR stripe
26
.
Magnetoresistive stripes
18
and
26
are used to read data from a magnetic disk in a manner well-known in the art. See, for example, U.S. Pat. No. 3,860,965, incorporated herein by reference. An insulating layer
32
(typically Al
2
O
3
) is formed on contact layers
30
a,
30
b
and a shared pole layer
34
(typically formed from a NiFe alloy) is formed on Al
2
O
3
insulating layer
32
. Of importance, bottom pole layer
14
and shared pole layer
32
(also known as first and second shield layers, respectively) filter the magnetic field from the magnetic disk. In this way, the magnetic field from data tracks adjacent to a track being read will not interfere with magnetoresistive stripes
18
and
26
.
A gap insulating layer
36
(typically Al
2
O
3
) is formed on shared pole layer
32
. Formed above gap insulating layer
36
is a top pole layer
38
. Shared pole layer
32
and top pole layer
38
serve as magnetic poles during writing operations.
FIG. 2
b
illustrates read-write element
2
in cross section along arrows B—B. As can be seen, top pole
38
extends upwardly and over a copper coil structure
40
that is used to generate a magnetic field during writing. Coil structure
40
is electrically insulated from top and shared pole layers
38
,
34
by insulating material
42
.
Referring back to
FIG. 2
a,
because of the uneven shape of the top surface of shared pole layer
34
, the gap between the top and shared pole layers
38
,
34
is curved, bending at points
3
a
and
34
b.
The shape of magnetic bits recorded in a magnetic disk by read-write head
2
is affected by the shape of the gap between top and shared pole layers
38
,
34
. In particular, since this gap is curved, the shape of the bits recorded in a disk therewith is curved. This curvature reduces the recording density that can be achieved. It is an object of our invention to eliminate this curvature. Eliminating the curvature in the gap permits us to increase recording density.
SUMMARY OF THE INVENTION
A method in accordance with our invention includes the steps of forming magnetoresistive stripes on a substrate, forming a shared pole layer above the magnetoresistive stripes, forming a gap layer above the shared pole layer, and forming a write pole layer above the gap layer. In accordance with one novel feature of our invention, the top surface of the shared pole layer is planarized prior to forming the gap layer. Accordingly, our invention has the effect of eliminating or substantially reducing curvature in the gap layer. Eliminating this curvature permits us to increase recording density. In one embodiment, planarization is accomplished by a mechanical-chemical planarization technique. In another embodiment, planarization is accomplished with an etch-back technique.
In one embodiment, at the conclusion of the planarization process, the roughness Ra of the shared pole layer is less than 0.1 microns, and typically less than 0.05 microns.


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patent: 4943882 (1990-07-01), Wada et al.
patent: 5068959 (1991-12-01), Sidman
patent: 5230833 (1993-07-01), Romberger et al.
patent: 5571373 (1996-11-01), Krishna et al.
patent: 5575837 (1996-11-01), Kodama et al.
Y. Hsu, et al. “Dual-Stripe MR Heads for One Gigabit per Inch Square Recording Density” Apr. 18, 1995.
Ali, et al., “Charged Partiles in Process Liquids”, Semiconductor International, Apr. 1990, pp. 92-95.
Carpio, R. et al “Initial Study on Copper CMP Slurry Chemistries”Thin Solid Film1995, pp. 238-244.
Sabde, G.M. Slurry Development For Chemical Mechanical Polishing of Tungsten, CMP-MIC Conference, 1997, pp. 331-334.
Pohl, M., et al., “The Importance of Particle Size to the Performance of Abrasive Particles in the CMP Process”, Journal of Electronic Materials, vol. 25, Nov. 10, 1996, pp. 1612-1616.
Vander Voort, G.F., “Polishing With Colloidal Silica”, 1997, pp. 1-13.
Ali, I., et al., “Chemical-Mechanical Polishing of Interlayer Dielectric: A review”,Solid-State TechnologyOct. 1994, pp. 63-70.
Niernynck, J.M., et al., The Addition of Surfactant to Slurry for Polymer CMP: Effects on Polymer Surface, Removal Rate and Underlying Cu,Thin Solid Films, 1996 pp. 447-452.
Hu, Z. Y. et al. “Chemical-Mechanical Polishing of PECVD Silicon Nitride”Thin Solid Films, 1996, pp. 453-457.
Thomas C. Anthony, et al., “Dual Stripe Magnetoresistive Heads for High Density Recording”, IEEE Transactions on Magnetics, Mar. 1994, vol. 30, No. 2, pp. 303-308.
K. Skidmore, “Techniques for Planarizing Device Topography”, Semiconductor International, Apr. 1988, pp. 115-119.

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