Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1999-04-01
2002-05-28
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S603150
Reexamination Certificate
active
06393692
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to thin film magnetoresistive (MR) heads and more particularly to magnetoresistive (MR) head structures.
2. Description of Related Art
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 structure formed by top shield and the flux enhancement layer. The flux enhancement layer is composed of a magnetic High Moment Material (HMM) such as FeN and CoNiFe formed over a magnetic Permalloy-Like Material (PLM) top shield layer. A flux enhanced data transducer and method for producing the same in conjunction with shared shields on magnetoresistive (MR) read heads (in which substantially between 500 521 -2500 Å of a relatively higher magnetic moment material such as FeN and CoNiFe is added to the upper surface of the shared shield, or bottom write head pole, prior to a magnetic flux containment ion milling operation utilizing the upper pole as a mask) are described. The relatively higher magnetic moment flux enhancement layer may comprise CoNiFe, FeN or similar material which is deposited prior to the formation of the dielec-tric gap layer. The upper pole may be formed of NiFe deposited on a thin film seed layer of a 1 Å thick layer of a material such as NiFe or “may also comprise FeN or other relatively higher magnetic moment material such as CoNiFe.” 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 1,000 Å of the layer need 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. 5,606,478 of Chen et al. for “Ni
45
Fe
55
Metal-in-Gap Thin Film Magnetic Head” and U.S. Pat. No. 5,812,350 of Chen et al. for “Metal-in-Gap Thin Film Magnetic Head Employing Ni
45
,Fe
55
” show a pole piece P1 composed of a combination of HMM and LMM materials.
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.
SUMMARY OF THE INVENTION
With the continuous trend in the magnetic recording industry of increasing of the track density of magnetic recording, the objective of reduction of edge erasure from adjacent track writing becomes increasingly important. Edge erasure, resulting from writing fringe, can decrease the written track width and 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 the heads made of High Moment Material (HMM) for write poles and Permalloy-Like Material (PLM) for magnetoresistive (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 a merged magnetoresistive (MR) recording heads with both High saturation Moment Material (HMM) and Permalloy. The HMM material is suitable for recording on high-coercivity media. Permalloy or Permalloy-Like Material (PLM) can function as a good sensor shield.
GLOSSARY
Edge erasure . . . Erasure by the write head that occurs outside of two edges of the the write track.
Writing fringe . . . Unintended writing along two edges of the desired write track.
Writing fringe-field . . . the magnetic field outside of the write gap causing inadvertent writing along two edges of the desired write track.
Overwrite . . . The process of writing on a disk track to erase previously written information while simultaneously writing new data.
Side writing . . . Unintended writing on two sides of a track. It may adversely affect data recorded on an adjacent track.
HMM . . . High Moment Material electroplated 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, with a ratio just below 5:1 Ni atoms to Fe atoms, Ni
79
Fe
9
.
Permalloy Like Material—PLM
PLM . . . Permalloy Like Material consists of all electroplated metals and alloys having soft-magnetic properties 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 over a substrate.
Form a read gap layer with a magnetoresistive head over the first shield layer.
Form a seed layer over the read gap layer.
Form a frame mask with width “W” over the seed layer.
Form a low magnetic moment second magnetic shield layer over the read gap layer over the seed layer.
Form a non-magnetic spacer layer over the second magnetic shield layer.
Form a first high magnetic moment pole layer over the second magnetic shield layer.
Form a write gap layer over the first high magnetic moment pole layer.
Form a second high magnetic moment pole layer over the write gap layer.
Outside of the frame mask perform the step of removing the portions the second magnetic shield layer, the first high magnetic moment pole layer, the write gap layer, the second high magnetic moment pole, and the seed layer.
Preferably, employ ion beam etching to narrow the lower pole layer and the write gap layer to upper magnetic pole width “N” where width “W” is substantially greater than width “N”, and employ ion beam etching to pattern the first high magnetic moment pole layer to magnetic pole width “N” in part and flaring the remainder of the first high magnetic moment pole layer towards the width “W” of the second magnetic shield layer. As a result, the upper high magnetic moment pole layer has a narrow width “N”, the second magnetic shield layer has a width “W” over the second magnetic shield layer. Narrow the lower pole layer and the write gap layer to upper magnetic pole width “N” where width “W” is substantially greater than width “N”, and pattern the first high magnetic moment pole layer to magnetic pole width “N” in part and flaring the remainder of the first high magnetic moment pole layer towards the width “W” of the second magnetic shield layer. This structure is fashioned by using the upper pole as a mask to trim the upper high magnetic moment layer of the shared pole so that the high magnetic moment layer has the same dimension “N” as the top pole and its bottom part is wider with a width “W”.
Form a nonmagnetic spacer layer over the low magnetic moment, second magnetic shield layer, and below the lower pole layer.
The low magnetic moment second magnetic shield layer over the read gap layer is formed of a material selected from the group consisting of metals and alloys having soft-magnetic properties including Permalloy, NiFeCr, NiFeMo, NiFeW, NiFePd, NiFeCu, and NiFeCo, and the lower pole layer is formed of a material selected from the group consisting of Ni
45
Fe
55
, Ni
45
Fe
55
Sn, CoNiFe, CoFeCu, Ni
45
Fe
55
Cr, and Ni
45
Fe
55
Mo.
Sputter a PLM nickel-iron seed layer over the read gap layer prior to plating the low magnetic moment second magnetic shield layer.
Another aspect of this invention is the merged magnetic read head/write head structure produced by the above process.
REFERENCES:
patent: 5435053 (1995-07-01), Krounbi et al.
patent: 5606478 (1997-02-01), Chen et al.
patent: 5639509 (1997-06-01), Schemmel
patent: 5812350 (1998-09-01), Chen et al.
patent: 6047462 (2000-04-01), Miyauchi et al.
patent: 6119331 (2000-09-01), Chang et al.
Chang Jei-Wei
Chen Mao-Min
Han Cherng-Chyi
Ju Kochan
Liu Chun
Ackerman Stephen B.
Arbes Carl J.
Headway Technologies Inc.
Jones II Graham S.
Saile George O.
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