Double plate-up process for fabrication of composite...

Details Double plate-up process for fabrication of composite... Double plate-up process for fabrication of composite...

1999-04-26

2003-02-25

Mills, Gregory (Department: 1746)

Etching a substrate: processes

Forming or treating article containing magnetically...

C216S038000, C216S057000, C216S066000, C029S603010, C029S603070, C360S317000

Reexamination Certificate

active

06524491

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to thin film heads and more particularly to magnetoresistive (MR) thin film heads.
2. Description of Related Art
U.S. Pat. No. 5,435,053 of Krounbi et al. for “Simplified Method of Making Merged MR Head” shows a method for making a planarized merged pole.
U.S. Pat. No. 5,639,509 of Schemmel for “Process for Forming a Flux Enhanced Magnetic Data Transducer” shows a two layered bottom pole formed by a top shield composed of an NiFe layer
42
covered with a pole layer
48
for an inductive read head formed of a thin flux enhancement layer with relatively High Magnetic Moment (HMM). As to the NiFe layer
42
, ratio of Ni to Fe in the composition is unspecified. This is a flux enhanced data transducer and method for producing the same in conjunction with shared shields on MR read heads. Between 500 Å-2500 Å of a HMM material
48
is added to the upper surface of the shared shield
42
, to form the bottom pole of an inductive write head
40
pole, prior to a magnetic flux containment ion milling operation utilizing the upper pole as a mask. The HMM flux enhancement layer
42
, which may be composed of FeN, CoNiFe or other higher magnetic moment materials, is deposited prior to the formation of the dielectric gap layer. The flux enhancement layer may then be selectively removed substantially surrounding the upper pole by means of a relatively brief ion milling process in which only on the order of 1.0 kÅ of the layer needs to be removed and during which only an insignificant amount of the material removed might be re-deposited on the sides of the upper pole.
U.S. Pat. No. 5,750,275 of Katz et al. for “Thin Film Heads with Insulated Laminations for Improved High Frequency Performance” shows a laminated magnetic pole member using an alumina (Al
2
O
3
) insulating layer.
U.S. Pat. No. 5,606,478 of Chen et al. for “Ni
45
Fe
55
Metal-in-Gap Thin Film Magnetic Head” shows a composite structure with an MR magnetic read head with an MR stripe and an inductive magnetic read head. Between the MR head and the inductive head is a pole piece composed of a combination of High Magnetic Moment (HMM) and PERMALLOY-Like Material (PLM) with Low Magnetic Moment (LMM) laminated together. The MR head includes two magnetic shields with the lower one formed on the substrate. A shared shield/pole includes the upper magnetic shield of the MR head formed in a composite structure with the lower pole of the inductive magnetic read head. The shared PLM shield/HMM pole which is formed of plated thick layer of Ni
80
Fe
20
which is a PLM material/with a plated thin layer of Ni
45
Fe
55
which is an HMM material.
SUMMARY OF THE INVENTION
With the continuous trend in the magnetic recording industry towards increasing the track density of magnetic recording, it becomes increasingly important to reduce edge erasure from adjacent track writing. Edge erasure, resulting from writing fringe, can decrease the written track width and can reduce drive yield by degrading off-track capacity and/or unwanted overwriting of adjacent tracks when writing. The writing fringe field often comes from a dimensional inconsistency and a mismatch of materials near the area where the flux is crowded, i.e. the gap area, of write heads. Recording on high-coercivity media especially requires magnetic recording heads made of High Moment Material (HMM) for write poles and PERMALLOY Material (PLM) for MR shields.
Magnetic poles made of materials with a saturation magnetization higher than that of PERMALLOY are desirable for improving the writability of magnetic recording heads.
We have found that there is a need for merged MR recording heads with both High saturation Moment Material (HMM) and PERMALLOY for a shared pole. The HMM material is suitable for recording on high-coercivity media. PERMALLOY or PERMALLOY-Like Material (PLM) can function as a good sensor shield.
Materials with a saturation magnetization higher than that of PERMALLOY (Ni
79
Fe
21
alloy) are desired for improving the writability of recording heads. A considerable need has led towards the direction of producing magnetoresistive (MR) merged recording heads with High saturation Moment (4&pgr;M
s
) Material (HMM) and PERMALLOY.
PERMALLOY or PERMALLOY-like materials (PLMs) can function as a good sensor shields. A copending commonly assigned application Ser. No. 09/283,840 filed on Apr. 1, 1999, now U.S. Pat. No. 6,393,692 entitled “Method of Manufacture of a Composite Shared Pole Design for MR Merged Heads and Device Manufactured Thereby” has a shared pole design which minimizes the effects of dimension change and material mismatch on side writing. The subject matter thereof is Incorporated herein by reference.
Due to the improvement of head performance, we find that planarization of a shared pole is useful for flattening topography resulting from MR and conductors.
When using a metal planarization process, it is difficult to obtain good uniformity across the wafer. The variation in thickness can be as large as ±0.7 &mgr;m which results in large variations in the thickness of the top, HMM layer if the planarization process is to be applied after both the PML layer and the HMM layer were formed. The thickness of the HMM layer is critical for eliminating saturation, which can cause a large writing fringe field.
GLOSSARY
Edge erasure
Erasure of the edge of an adjacent
track when writing on a track
Writing fringe
Writing on the fringe of a track
from an adjacent
Overwrite
The process of writing on a disk
track to erase previously written
information while simultaneously
writing new data.
Side writing
Writing on the side of a track
which adversely affects data
recorded on an adjacent track.
HMM
High Moment Material of metals and
alloys having high saturation
moments or saturation magnetization
(4&pgr;M
s
) characteristics such as
Ni
45
Fe
55
, Ni
45
Fe
55
Sn, CoNiFe,
CoFeCu, Ni
45
Fe
55
Cr, and Ni
45
Fe
55
Mo.
PERMALLOY
A nickel rich alloy with iron Ni
79
Fe
19
with a ratio
just below 5:1 Ni atoms to Fe atoms.
PERMALLOY
PLM
Like Material
PLM
PERMALLOY Like Material consists of all metals
and alloys having soft-magnetic properties (including
PERMALLOY) such as PERMALLOY (Ni
79
Fe
19
),
NiFeCr, NiFeMo, NiFeW, NiFePd NiFeCu, NiFeCo
in which the ratio of nickel atoms to iron atoms
is about 5:1 with fewer high magnetic moment
iron atoms.
ABS
Air Bearing Surface - pole tips are
separated by an air gap at an ABS.
IBE
Ion Beam Etching
A method of manufacturing a magnetic recording head includes the following steps. Form a low magnetic moment, first magnetic shield layer (S
1
) over a substrate.
Form a read gap layer (RG) with a magnetoresistive head over the first shield layer (Si). Then form a seed layer (SL) over the read gap layer (RG). Next, form a frame mask (PR) with width (F) over the seed layer (SL). Form a low magnetic moment, second magnetic shield layer (S
2
A) over the seed layer (SL), which is over the read gap layer (RG). Planarize the low magnetic moment, second magnetic shield layer (S
2
A). Preferably, form a non-magnetic spacer metal or metal alloy layer (SP), preferably composed of copper, over the second magnetic shield layer. Then form a lower, first high magnetic moment, lower pole layer (S
2
B) over the second magnetic shield layer (S
2
A), preferably over the non-magnetic spacer metal or metal alloy layer (SP).
Then, form a second mask covering a portion of the structure defined by the frame mask. Then, outside of the second frame mask, remove the portions the upper, second high magnetic moment, pole (UP), the write gap layer (WG), the first high magnetic moment, lower pole layer (S
2
B), the second magnetic shield layer (S
2
A), and the seed layer (SL).
FIGS. 1A-1I
shows successive steps in a process of manufacturing a device shown in
FIG. 2
in accordance with the method of this invention.
FIG. 1I
shows a section taken along line
1
—
1
in FIG.
2
.
FIGS. 1A-1H
show a series of sections taken generally along line
1
—
1
of
FIG. 2
in various earlier stage

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