U.S. patent application number 09/773743 was filed with the patent office on 2001-11-15 for method of fabrication of striped magnetoresistive (smr) and dual stripe magnetoresistive (dsmr) heads with anti-parallel exchange configuration.
This patent application is currently assigned to HEADWAY TECHNOLOGIES, INC.. Invention is credited to Chang, Jei-Wei, Chen, Mao-Min, Horng, Cheng T., Ju, Kochan.
Application Number | 20010040782 09/773743 |
Document ID | / |
Family ID | 23616495 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040782 |
Kind Code |
A1 |
Ju, Kochan ; et al. |
November 15, 2001 |
Method of fabrication of striped magnetoresistive (SMR) and dual
stripe magnetoresistive (DSMR) heads with anti-parallel exchange
configuration
Abstract
A method for forming a longitudinally magnetically biased dual
stripe magnetoresistive (DSMR) sensor element comprises forming a
first patterned magnetoresistive (MR) layer. Contact the opposite
ends of the patterned magnetoresistive (MR) layer with a first pair
of stacks defining a track width of the first magnetoresistive (MR)
layer, each of the stacks including a first Anti-Ferro-Magnetic
(AFM) layer and a first lead layer. Then anneal the device in the
presence of a longitudinal external magnetic field. Next, form a
second patterned magnetoresistive (MR) layer above the previous
structure. Contact the opposite ends of the second patterned
magnetoresistive (MR) layer with a second pair of stacks defining a
second track width of the second patterned magnetoresistive (MR)
layer. Each of the second pair of stacks includes spacer layer
composed of a metal, a Ferro-Magnetic (FM) layer, a second
Anti-Ferro-Magnetic (AFM) layer and a second lead layer. Then
anneal the device in the presence of a second longitudinal external
magnetic field.
Inventors: |
Ju, Kochan; (Fremont,
CA) ; Chen, Mao-Min; (San Jose, CA) ; Horng,
Cheng T.; (San Jose, CA) ; Chang, Jei-Wei;
(Cupertino, CA) |
Correspondence
Address: |
George O. Saile
20 McIntosh Drive
Poughkeepsie
NY
12603
US
|
Assignee: |
HEADWAY TECHNOLOGIES, INC.
|
Family ID: |
23616495 |
Appl. No.: |
09/773743 |
Filed: |
February 2, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09773743 |
Feb 2, 2001 |
|
|
|
09408491 |
Sep 30, 1999 |
|
|
|
6204071 |
|
|
|
|
Current U.S.
Class: |
360/327.3 ;
360/315; 438/3; G9B/5.116 |
Current CPC
Class: |
B82Y 10/00 20130101;
G11B 5/3932 20130101; G11B 5/3163 20130101; G11B 5/3903 20130101;
G11B 2005/3996 20130101; B82Y 25/00 20130101; G11B 5/3948
20130101 |
Class at
Publication: |
360/327.3 ;
438/3; 360/315 |
International
Class: |
H01L 021/00; G11B
005/39 |
Claims
Having thus described the invention, what is claimed as new and
desirable to be secured by Letters Patent is as follows:
1. A method for forming a longitudinally magnetically biased stripe
magnetoresistive sensor element comprising: forming a first
patterned magnetoresistive (MR) layer, contacting a pair of
opposite ends of said patterned magnetoresistive (MR) layer with a
pair of stacks defining a track width of said patterned
magnetoresistive (MR) layer, each of said stacks including as
follows: a spacer layer composed of a metal, a Ferro-Magnetic (FM)
layer, an Anti-Ferro-Magnetic (AFM) layer and a lead layer, and
annealing said device in the presence of a longitudinal external
magnetic field.
2. A method in accordance with claim 1 wherein said spacer layer is
composed of a metal selected from the group consisting of ruthenium
(Ru), rhodium (Rh), copper (Cu) and chromium (Cr).
3. A method in accordance with claim 1 wherein said Ferro-Magnetic
layer is composed of a metal selected from the group consisting of
NiFe, Co, Fe, NiCo and CoFe.
4. A method in accordance with claim 1 wherein said AFM layer is
composed of a metal selected from the group consisting of IrMn,
NiMn, PtMn, PdPtMn and FeMn.
5. A method in accordance with claim 1 wherein: said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr), and
said Ferro-Magnetic layer is composed of a metal selected from the
group consisting of NiFe, Co, Fe, NiCo and CoFe.
6. A method in accordance with claim 1 wherein: said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru) rhodium (Rh), copper (Cu) and chromium (Cr), said
Ferro-Magnetic layer is composed of a metal selected from the group
consisting of NiFe, Co, Fe, NiCo and CoFe, and said AFM layer is
composed of a metal selected from the group consisting of IrMn,
NiMn, PtMn, PdPtMn and FeMn.
7. A method for forming a longitudinally magnetically biased dual
stripe magnetoresistive (DSMR) sensor element comprising: forming a
first patterned magnetoresistive (MR) layer, contacting a pair of
opposite ends of said patterned magnetoresistive (MR) layer with a
first pair of stacks defining a track width of said patterned
magnetoresistive (MR) layer, each of said stacks including as
follows: a first Anti-Ferro-Magnetic (AFM) layer and a first lead
layer, and annealing said device in the presence of a longitudinal
external magnetic field, forming a second patterned
magnetoresistive (MR) layer, contacting a pair of opposite ends of
said second patterned magnetoresistive (MR) layer with a second
pair of stacks defining a second track width of said second
patterned magnetoresistive (MR) layer, each of said second pair of
stacks including as follows: a spacer layer composed of a metal, a
Ferro-Magnetic (FM) layer, a second Anti-Ferro-Magnetic (AFM) layer
and a second lead layer, and annealing said device in the presence
of a second longitudinal external magnetic field.
8. A method in accordance with claim 7 wherein said spacer layer is
composed of a metal selected from the group consisting of ruthenium
(Ru), rhodium (Rh), copper (Cu) and chromium (Cr).
9. A method in accordance with claim 7 wherein said Ferro-Magnetic
layers are composed of a metal selected from the group consisting
of NiFe, Co, Fe, NiCo and CoFe.
10. A method in accordance with claim 7 wherein said AFM layers are
composed of a metal selected from the group consisting of IrMn,
NiMn, PtMn, PdPtMn and FeMn.
11. A method in accordance with claim 7 wherein: said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr), and
said Ferro-Magnetic layers are composed of a metal selected from
the group consisting of NiFe, Co, Fe, NiCo and CoFe.
12. A method in accordance with claim 7 wherein: said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr), said
Ferro-Magnetic layers are composed of a metal selected from the
group consisting of NiFe, Co, Fe, NiCo and CoFe, and said AFM
layers are composed of a metal selected from the group consisting
of IrMn, NiMn, PtMn, PdPtMn and FeMn.
13. A longitudinally magnetically biased stripe magnetoresistive
sensor element comprising: a first patterned magnetoresistive (MR)
layer, a pair of opposite ends of said first patterned
magnetoresistive (MR) layer contacted with a pair of stacks
defining a first track width of said first patterned
magnetoresistive (MR) layer, each of said stacks including as
follows: a spacer layer composed of a metal, a Ferro-Magnetic (FM)
layer, an Anti-Ferro-Magnetic (AFM) layer a lead layer, and said
device having a longitudinal magnetic bias.
14. A device in accordance with claim 13 wherein said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr).
15. A device in accordance with claim 13 wherein said
Ferro-Magnetic layer is composed of a metal selected from the group
consisting of NiFe, Co, Fe, NiCo and CoFe.
16. A device in accordance with claim 13 wherein said AFM layer is
composed of a metal selected from the group consisting of IrMn,
NiMn, PtMn, PdPtMn and FeMn.
17. A device in accordance with claim 13 wherein: said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr), and
said Ferro-Magnetic layer is composed of a metal selected from the
group consisting of NiFe, Co, Fe, NiCo and CoFe.
18. A device in accordance with claim 13 wherein: said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru) rhodium (Rh), copper (Cu) and chromium (Cr), said
Ferro-Magnetic layer is composed of a metal selected from the group
consisting of NiFe, Co, Fe, NiCo and CoFe, and said AFM layer is
composed of a metal selected from the group consisting of IrMn,
NiMn, PtMn, PdPtMn and FeMn.
19. A device for a longitudinally magnetically biased dual stripe
magnetoresistive (DSMR) sensor element comprising: a first
patterned magnetoresistive (MR) layer, a pair of opposite ends of
said first patterned MR layer being in contact with a first pair of
stacks defining a first track width of said patterned MR layer,
each of said stacks including as follows: a first
Anti-Ferro-Magnetic (AFM) layer and a first lead layer, and said
device having a first longitudinal magnetic field bias in said
first AFM layer, a second patterned MR layer, contacting a pair of
opposite ends of said second patterned MR layer with a second pair
of stacks defining a second track width of said second patterned MR
layer, each of said second pair of stacks including as follows: a
spacer layer composed of a metal, a Ferro-Magnetic (FM) layer, a
second AFM layer and a second lead layer, and said device having a
second longitudinal magnetic field bias in said second AFM
layer.
20. A device in accordance with claim 19 wherein said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr).
21. A device in accordance with claim 19 wherein said
Ferro-Magnetic layers are composed of a metal selected from the
group consisting of NiFe, Co, Fe, NiCo and CoFe.
22. A device in accordance with claim 19 wherein said AFM layers
are composed of a metal selected from the group consisting of IrMn,
NiMn, PtMn, PdPtMn and FeMn.
23. A device in accordance with claim 19 wherein: said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr), and
said Ferro-Magnetic layers are composed of a metal selected from
the group consisting of NiFe, Co, Fe, NiCo and CoFe.
24. A device in accordance with claim 19 wherein: said spacer layer
is composed of a metal selected from the group consisting of
ruthenium (Ru), rhodium (Rh), copper (Cu) and chromium (Cr), said
Ferro-Magnetic layers are composed of a metal selected from the
group consisting of NiFe, Co, Fe, NiCo and CoFe, and said AFM
layers are composed of a metal selected from the group consisting
of IrMn, NiMn, PtMn, PdPtMn and FeMn.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to Striped Magnetoresistive (SMR)
heads and Dual Stripe Magnetoresistive (DSMR) heads and more
particularly to methods of manufacturing of exchange biasing
configurations therefor, as well as devices manufactured by such
methods.
[0003] 2. Description of Related Art
[0004] As the continuous trend in magnetic recording requires
increased area density, track widths of magnetic recording heads
are being reduced. Commonly assigned U.S. patent application No.
09/182,775, filed Oct. 30, 1998 of Yimin Guo et al. for
"Anti-Parallel Longitudinal Patterned Exchange Biased Dual Stripe
Magnetoresistive (DSMR) Sensor Element and Method for Fabrication
Thereof" describes a narrow track width DSMR head with dual
sensors. The head, which increases signal amplitude is stabilized
by anti-parallel biasing, i.e. with biasing which is parallel, but
in the opposite directed or oriented. In such a biasing scheme, the
magnetic centers of dual sensors self-align each other.
[0005] Accordingly, no track-offsetting is needed as disclosed in
commonly assigned U.S. Pat. No. 5,783,460 of Han et al. for "Method
of Making Self-Aligned Dual Stripe MagnetoResistive (DSMR) Head for
High Density Recording" which shows a DSMR process using a lift off
stencil to form a patterned dielectric layer edge. To achieve this
quiescent biasing scheme, one can produce both sensors with
Anti-Parallel EXchange-biasing (APEX) by means of exchange coupling
between Anti-Ferro-Magnetic (AFM) and Ferro-Magnetic (FM)
material.
[0006] U.S. Pat. No. 5,408,377 of Gurney et al. for
"Magnetoresistive Sensor with Ferromagnetic Sensing Layer " shows a
Ruthenium (Ru) AFM coupling film in a spin valve sensor.
[0007] U.S. Pat. No. 5,644,456 of Smith et al. for "Magnetically
Capped Dual Magnetoresistive Reproduce Head" shows a cap layer in a
DSMR that breaks exchange coupling between the magnetically
permeable layer and MR elements.
[0008] U.S. Pat. No. 5,684,658 of Shi et al. for "High Track
Density Dual Stripe Magnetoresistive (DMSR) Head" shows a DSMR
having first and second anti-Ferro-Magnetic longitudinal biasing
layers.
[0009] U.S. Pat. No. 5,731,936 of Lee et al. for "Magnetoresistive
(MR) Sensor with Coefficient Enhancing that Promotes Thermal
Stability" provides chromium based spacer layers for an MR layer of
NiCr or NiFeCr compositions in place of Ta spacers to avoid a
reported problem of degrading the magnetic moment of the MR stripe
when high heat at the interface between the Ta spacer layer and the
Permalloy (MR stripe) causing interdiffusion therebetween.
[0010] See Parkin, "Systematic Variation of the Strength and
Oscillation Period of Indirect Magnetic Exchange Coupling through
the 3d. 4d and 5d Transition Metals", Physical Review Letters Vol.
67, No. 25, pp. 3598-3601 (Dec. 16, 1991)
[0011] U.S. Pat. No. 5,766,780 of Huang et al. for "Reversed Order
NiMn Exchange Biasing for Dual Magnetoresistive Heads" teaches a
DSMR with a Mo layer as the conductor/seed layer on an alumina base
coat. A NiMn exchange bias layer is formed on the Mo layer. A NiFe
MR sensor layer is formed on the surface of the NiMn exchange bias
layer.
SUMMARY OF THE INVENTION
[0012] This invention teaches a Ruthenium/Ferro-Magnetic/AFM three
layer structure to replace an AFM in a sensor in an MR or DSMR. In
the case of a DSMR, when one magnetically aligns both AFM in the
same direction, the biasing direction of the MR sensor under the
ruthenium will be anti-parallel to the other one. A key element of
the invention is the Ru spacer that shows increased coupling
strength.
[0013] In accordance with this invention a method is provided for
forming a longitudinally magnetically biased dual stripe
magnetoresistive (DSMR) sensor element comprises forming a first
patterned magnetoresistive (MR) layer. Contact the opposite ends of
the patterned magnetoresistive (MR) layer with a first pair of
stacks defining a track width of the first magnetoresistive (MR)
layer, each of the stacks including a first Anti-Ferro-Magnetic
(AFM) layer and a first lead layer. Then anneal the device in the
presence of a longitudinal external magnetic field. Next, form a
second patterned magnetoresistive (MR) layer above the previous
structure. Contact the opposite ends of the second patterned
magnetoresistive (MR) layer with a second pair of stacks defining a
second track width of the second patterned magnetoresistive (MR)
layer. Each of the second pair of stacks includes spacer layer
composed of a metal, a Ferro-Magnetic (FM) layer, a second
Anti-Ferro-Magnetic (AFM) layer and a second lead layer. Then
anneal the device in the presence of a second longitudinal external
magnetic field.
[0014] In accordance with another aspect of this invention, a
longitudinally magnetically biased dual stripe magnetoresistive
(DSMR) sensor element is provided including a first patterned
magnetoresistive (MR) layer. There are a pair of opposite ends of
the first patterned MR layer being in contact with a first pair of
stacks defining a first track width of the patterned MR layer. Each
of the stacks includes a first AFM layer and a first lead layer.
The device has a first longitudinal magnetic field bias in the
first AFM layer. There is a second patterned MR layer contacted at
its opposite ends by a second pair of stacks defining a second
track width of the second patterned MR layer. Each of the second
pair of stacks includes a spacer layer composed of a metal, a
Ferro-Magnetic (FM) layer, a second AFM layer and a second lead
layer. The device has a second longitudinal magnetic field bias in
the second AFM layer. Preferably, the spacer layer is composed of a
metal selected from the group consisting of ruthenium (Ru), rhodium
(Rh), copper (Cu) and chromium (Cr). It is also preferred that the
Ferro-Magnetic layers are composed of a metal selected from the
group consisting of NiFe, Co, Fe, NiCo and CoFe. Moreover, it is
preferred that the AFM layers are composed of a metal selected from
the group consisting of IrMn, NiMn, PtMn, PdPtMn and FeMn.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The foregoing and other aspects and advantages of this
invention are explained and described below with reference to the
accompanying drawings, in which:
[0016] FIG. 1 illustrates an application of an exchange biasing
structure of a
Ferro-Magnetic/spacer/Ferro-Magnetic/Anti-Ferro-Magnetic
(MR/SP/FM/AFM) for biasing a single MR sensor longitudinally in
accordance with this invention.
[0017] FIGS. 2A-2D show a method of employing the method of this
invention in a Dual Stripe Magneto-Resistive (DSMR) head
application, in which one can replace the bias structure of one of
sensors by the multi-layer structure of this invention as
illustrated by FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] In accordance with this invention, to fabricate an
Anti-Parallel EXchange-biasing (APEX) head, two Anti-Ferro-Magnetic
(AFM) layers with a distinct difference in blocking temperatures
are selected. We find that by annealing at two different
temperatures, one achieves an APEX state in a Dual Stripe
Magneto-Resistive (DSMR) head. Another approach is to use the same
AFM material in the biasing layers. The AFM layer of the first MR
sensor is annealed in a desired first direction of magnetization.
We also find that the AFM layer of the second MR sensor is
consequently annealed in the opposite direction without degrading
the exchange magnetic field magnitude and direction of first AFM
layer of the first MR sensor.
[0019] We find, in addition, that APEX heads manufactured by these
methods require a magnetic initialization process to set sensors
back to APEX state. Further in accordance with this invention, the
longitudinal switch threshold magnetic field for two MR sensors can
be determined. Our specific recipe of longitudinal magnetic field
provides a sequence for tailoring the exchange magnetic field,
coercivity and annealing conditions.
[0020] In a GMR device, a strong interlayer coupling which is known
as Anti-Parallel Ferro-Magnetic Interlayer (APFI) coupling, can be
used in a sandwiched structure of
Ferro-Magnetic/spacer/Ferro-Magnetic layers. When depositing an AFM
layer onto such a sandwiched structure, a strong AFM layer
magnetization pins the magnetization of its neighboring magnetic
layer. The bottom Ferro-Magnetic layer is in an APFI coupling
state.
[0021] In the embodiment of this invention shown in FIG. 1, net
magnetic flux is determined from the difference of magnetic moment
of bottom and top Ferro-Magnetic layers which comprise the
magnetoresistive layer MR on the bottom and Ferro-Magnetic layers
FL/FR on the top.
[0022] FIG. 1 illustrates an application of an exchange biasing
structure of a
Ferro-Magnetic/spacer/Ferro-Magnetic/Anti-Ferro-Magnetic
(MR/SP/FM/AFM) for biasing a single MR sensor longitudinally in
accordance with this invention. The device of FIG. 1 includes a
substrate SUB upon which is formed a shield layer SHL upon which a
first non-magnetic spacer layer NMS is formed. The magnetoresistive
sensor MR is formed on the first non-magnetic spacer layer NMS.
Refill layers RFL and RFR are formed on the surface of the left and
right ends of magnetoresistive sensor MR and a set of second
non-magnetic spacer layers SL and SR are formed on the surfaces of
the refill layers RFL and RFR above the magnetoresistive sensor MR.
Above the second non-magnetic spacer layers SL and SR are formed a
set of Ferro-Magnetic layers FL and FR upon which are formed
exchange biasing Anti-Ferro-Magnetic (AFM) layers AL and AR which
overlie the ends of layers FL and FR. In turn leads LL, and LR have
been formed over the AFM layers AL and AR respectively.
[0023] The exchange biasing AFM layers AL and AR are shown after
annealing in the presence of an externally applied magnetic field
H.alpha. shown in phantom (since it is no longer present) which has
produced a longitudinal biasing magnetic field from left to right
in the Ferro-Magnetic layers FL and FR with reversely directed,
pinned magnetic fields in the Ferro-Magnetic layers FL and FR above
the ends of magnetoresistive sensor MR. The magnetic fields of the
Ferro-Magnetic, magnetoresistive sensor layer MR causes a resultant
matching and opposite, magnetic field from right to left in the
magnetoresistive sensor MR.
[0024] In practice, the net magnetic flux of the structure is
needed to stabilize and bias the magnetoresistive sensor MR. The
net magnetic flux is determined from the difference of magnetic
moment of bottom Ferro-Magnetic magnetoresistive sensor MR and the
top Ferro-Magnetic layers FL and FR.
[0025] FIGS. 2A-2D show a method of employing the method of this
invention in a Dual Stripe MR (DSMR) head application, in which one
can replace the bias structure of one of sensors by the multi-layer
structure of this invention as illustrated by FIG. 1. When we reset
the bias direction, both sensors MR1 and MR2 will be automatically
biased in anti-parallel directions as seen in FIG. 2D. This
structure can also greatly simplify the annealing process and can
also greatly simplify the initialization process.
[0026] The Anti-Parallel (AP) initialization becomes simple, since
both Anti-Parallel Magnetizations (APM) are in a unique direction.
After completing all the necessary thermal cycles for wafer
fabrication, the wafer will be annealed in a high longitudinal
magnetic field which is slightly larger than shield saturation (the
value is depend on shield material and design). The sensor
magnetization can be reset accordingly.
Process Steps
[0027] FIG. 2A shows a device 20 being manufactured in accordance
with the method of this invention. A substrate SUB composed of a
material such as a ceramic, e.g. alumina (Al.sub.2O.sub.3),
titanium carbide (TiC), has been coated with a shield layer SHL
preferably composed of a ferromagnetic material such as Permalloy
(NiFe, 80:20). Upon the shield layer a spacer layer SP is formed
composed of a non-magnetic material, e.g. alumina
(Al.sub.2O.sub.3), silicon oxide (SiO.sub.2) or silicon nitride
(Si.sub.3N.sub.4). Upon the spacer layer SP a first
magnetoresistive sensor layer MR1 is formed composed of a
Ferro-Magnetic material such as Permalloy (NiFe, 80:20), Co, Fe,
NiCo, or CoFe.
[0028] Next, on the left and right ends of the magnetoresistive
sensor MR1 a pair of stacks are formed on the top surface of
magnetoresistive sensor MR1 with a track width TW1 formed
therebetween, conventional processing techniques such as a lift-off
process.
[0029] In the stack on the left, there are three layers starting
with the refill layer RF1 (RL1 in FIG. 2D) formed of NiFe/80:20 on
the surface of magnetoresistive sensor MR1 followed by the left AFM
layer ALL preferably formed of a material selected from the group
consisting of IrMn, NiMn, PtMn, PdPtMn and FeMn. On top of the left
AMF layer ALL is the left lead line LLL, preferably formed of
copper.
[0030] In the stack on the right, there are three layers starting
with the refill layer RR1 formed of NiFe/80:20 on the surface of
the right end of the magnetoresistive sensor MR1 followed by the
right AFM layer ARL preferably formed of a material selected from
the group consisting of IrMn, NiMn, PtMn, PdPtMn and FeMn. On top
of the right AMF layer ARL is the right lead line LLR, preferably
formed of copper.
[0031] FIG. 2B shows the device of FIG. 2A after having been
annealed in the presence of an externally applied magnetic field H1
shown in phantom (since it is no longer present) which has produced
a longitudinal biasing magnetic field from left to right in AFM
layers ALL and ARL producing a magnetic field from right to left in
the sensor MR1.
[0032] FIG. 2C shows the device of FIG. 2B after formation of the
remaining layers of the DSMR but prior to annealing of the AFM
layers thereof. First an intermediate dielectric layer ISD is
formed composed of a non-magnetic dielectric material, e.g. alumina
(Al.sub.2O.sub.3), silicon oxide (SiO.sub.2) or silicon nitride
(Si.sub.3N.sub.4).
[0033] Next, a second magnetoresistive sensor layer MR2 is formed
composed of a Ferro-Magnetic material such as Permalloy (NiFe,
80:20), Co, Fe, NiCo, or CoFe.
[0034] Next, on the left and right ends of the MR sensor MR2 an
upper pair of stacks are formed on the top surface of
Magneto-Resistive sensor MR2 with a track width TW2 formed
therebetween, conventional processing techniques such as a lift-off
process.
[0035] In the upper stack on the left, there are five layers
starting with the upper left refill layer RFU formed of NiFe/80:20
on the surface of magnetoresistive sensor MR2, followed by the
upper left spacer layer SRL formed preferably of ruthenium (Ru) or
at least one of rhenium (Rh), copper (Cu) or chromium (Cr). Above
the upper left spacer layer SLU is formed the upper left
Ferro-Magnetic layer FLU preferably composed of a Ferro-Magnetic
material such as Permalloy (NiFe, 80:20), Co, Fe, NiCo, or
CoFe.
[0036] Next follows the upper left AFM layer ALU preferably formed
of a material selected from the group consisting of IrMn, NiMn,
PtMn, PdPtMn and FeMn. On top of the upper left AMF layer ALU is
the upper left lead line LLU, preferably formed of gold.
[0037] In the upper stack on the right, there are five layers
starting with the upper right refill layer RRU formed of NiFe on
the surface of the right end of the magnetoresistive sensor MR2,
followed by the upper right spacer layer SRU formed preferably of
ruthenium (Ru) or at least one of rhodium (Rh), copper (Cu) or
chromium (Cr).
[0038] Next follows upper right Ferro-Magnetic layer FRU preferably
composed of a Ferro-Magnetic material such as Permalloy (NiFe,
80:20), Co, Fe, NiCo, or CoFe. Upon layer FRU is formed exchange
biasing Anti-Ferro-Magnetic (AFM) layers ALU, preferably formed of
a material selected from the group consisting of IrMn, NiMn, PtMn,
PdPtMn and FeMn. On top of the right AMF layer ARU is the right
lead line LLR, preferably formed of gold.
[0039] FIG. 2D shows the device of FIG. 2C after having been
annealed in the presence of an externally applied magnetic field H2
shown in phantom (since it is no longer present) which has produced
a longitudinal biasing magnetic field from left to right in the
Ferro-Magnetic layers layers FLU and FRU in the same direction
producing a magnetic field from right to left with reversely
directed, pinned magnetic fields from right to left in the sensor
MR2 and from right to left in the sensor MR1.
SUMMARY
[0040] In the sandwiched structure, there are coupling forces
between the magnetic layers that try to align their magnetization
directions to be either parallel (P) or anti-parallel (AP). With
increasing thicknesses of the spacers SL and SR, the P and AP will
be alternated. The most pronounced coupling effect is observed when
Ru was used as the spacer layer SL and SR. In this case, the
coupling strength can reach a level ten (10) times stronger than
that provided by a copper (Cu) spacer or other noble metals. The Ru
layer thickness can be selected so that the bottom layer will be in
an APF1 (Anti-Parallel Ferro-Magnetic Interlayer) coupling
state.
[0041] For a DSMR head dual MR layer structure, fabrication of the
AFM layer in one of the two MR sensors is replaced by
Ru/Ferro-Magnetic/AFM three layers. When we magnetically align two
AFM layers in the same direction, the biasing direction of the
sensor under the Ru layer will be automatically anti-parallel to
that the other one. Substitution for the Ru layer can be made by
metals selected from Rh, Cu and Ir. The Ferro-Magnetic film can be
made of a material selected from a metal such as Co or Fe or alloys
such as NiFe, NiCo and CoFe. The AFM layer can be composed of an
alloy such as IrMn, NiMn, PtMn, PdPtMn and FeMn, etc.
[0042] While this invention has been described in terms of the
above specific embodiment(s), those skilled in the art will
recognize that the invention can be practiced with modifications
within the spirit and scope of the appended claims, i.e. that
changes can be made in form and detail, without departing from the
spirit and scope of the invention. Accordingly, all such changes
come within the purview of the present invention and the invention
encompasses the subject matter of the claims which follow.
* * * * *