U.S. patent application number 11/862999 was filed with the patent office on 2008-01-17 for methods of manufacturing magnetic heads with reference and monitoring devices.
This patent application is currently assigned to Quantum Corporation. Invention is credited to Andrew L. Wu.
Application Number | 20080013219 11/862999 |
Document ID | / |
Family ID | 35344672 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080013219 |
Kind Code |
A1 |
Wu; Andrew L. |
January 17, 2008 |
METHODS OF MANUFACTURING MAGNETIC HEADS WITH REFERENCE AND
MONITORING DEVICES
Abstract
According to one aspect, an exemplary method for manufacturing a
magnetic head includes forming a plurality of magnetoresistive
devices, a reference device, and a monitoring device, where the
reference device includes a desired stripe height less than the
magnetoresistive devices and monitoring device. Material is removed
from the air/tape bearing surface, e.g., by lapping, thereby
reducing the stripe height of the magnetoresistive devices and
monitoring device. A characteristic of the reference device, e.g.,
resistance, voltage, or the like, is compared with a similar
characteristic of the monitoring device, wherein the characteristic
of the monitoring device varies as material is removed. Material
may be removed from the bearing surface until the characteristic of
the monitoring device and the reference device are substantially
equal, at which time, the stripe height of the monitoring device
and magnetoresistive devices are substantially equal to that of the
reference device.
Inventors: |
Wu; Andrew L.; (Shrewsbury,
MA) |
Correspondence
Address: |
MORRISON & FOERSTER LLP
755 PAGE MILL RD
PALO ALTO
CA
94304-1018
US
|
Assignee: |
Quantum Corporation
San Jose
CA
|
Family ID: |
35344672 |
Appl. No.: |
11/862999 |
Filed: |
September 27, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10917782 |
Aug 13, 2004 |
7290325 |
|
|
11862999 |
Sep 27, 2007 |
|
|
|
Current U.S.
Class: |
360/313 ;
G9B/5.094; G9B/5.095 |
Current CPC
Class: |
Y10T 29/49037 20150115;
Y10T 29/49041 20150115; G11B 5/3173 20130101; Y10T 29/49032
20150115; G11B 5/3163 20130101; Y10T 29/49048 20150115; G11B 5/3166
20130101; G11B 5/3169 20130101; Y10T 29/49046 20150115; Y10T
29/49052 20150115 |
Class at
Publication: |
360/313 |
International
Class: |
G11B 5/33 20060101
G11B005/33 |
Claims
1: A method for manufacturing a magnetic head, comprising: forming
a plurality of magnetoresistive devices, a reference device, and a
monitoring device on a substrate; removing material from a bearing
surface of the substrate, thereby reducing a stripe height of the
magnetoresistive devices; and comparing a characteristic of the
reference device with a characteristic of the monitoring device,
wherein the characteristic of the monitoring device varies as
material is removed from the bearing surface.
2: The method of claim 1, wherein the monitoring device is formed
having a stripe height greater than the reference device prior to
removing material.
3: The method of claim 1, wherein the monitoring device is formed
having a stripe height equal to a read element of the plurality of
magnetoresistive devices.
4: The method of claim 1, wherein the reference device is formed
having a stripe height defined by photolithographic processing.
5: The method of claim 1, wherein the monitoring device is formed
similarly to the magnetoresistive devices.
6: The method of claim 1, wherein the monitoring device and the
reference device are formed at the same level as the
magnetoresistive devices.
7: The method of claim 1, wherein the monitoring device and the
reference device are formed adjacent to and at the same pitch as
the magnetoresistive devices.
8: The method of claim 1, wherein the act of removing material from
the bearing surface includes lapping the surface.
9: The method of claim 1, wherein the characteristic of the
reference device and the characteristic of the monitoring device
includes an electrical measurement of the reference device and the
monitoring device.
10: The method of claim 1, further comprising sending at least one
electrical signal through the reference device and the monitoring
device to determine the characteristic of the reference device and
the characteristic of the monitoring device.
11: The method of claim 1, wherein the act of removing material
from the bearing surface is stopped when the characteristic of the
monitoring device is equal to the characteristic of the reference
device.
12: The method of claim 1, wherein the magnetoresistive devices
include anisotropic magnetoresistive devices or giant
magnetoresistive devices.
13: A magnetic head for use with magnetic storage media
manufactured by the method of claim 1.
14-19. (canceled)
20: A multi-channel magnetic recording head, comprising: a
plurality of magnetoresistive devices including a reader element
and a writer element; and a pair of electronic lapping guides
including a monitoring device and a reference device, wherein the
monitoring device and the reference device include a reader
element.
21: The magnetic recording head of claim 20, further comprising a
second pair of electronic lapping guides including a second
monitoring device and a second reference device.
22: The magnetic recording head of claim 20, wherein the monitoring
device and the reference device are disposed at the same level as
the reader element of the magnetoresistive devices.
23: The magnetic recording head of claim 20, wherein the monitoring
device and the reference device are disposed adjacent to and at the
same pitch as the magnetoresistive devices.
24: The magnetic recording head of claim 20, wherein the
magnetoresistive devices include anisotropic magnetoresistive
devices or giant magnetoresistive devices.
25: The magnetic recording head of claim 20, wherein the width of
the monitoring device and the reference device is equal to or
greater than the width of the reader element of the plurality of
magnetoresistive devices.
26: The magnetic recording head of claim 20, wherein the width of
the monitoring device and the reference device is greater than the
width of the reader element of the plurality of magnetoresistive
devices.
27: The magnetic recording head of claim 20, wherein the monitoring
device and the reference device are used during a lapping process
to determine the relative height of the reference device to the
monitoring device.
Description
BACKGROUND
[0001] 1. Field
[0002] The present invention relates generally to magnetic
read/write heads and methods of manufacture, and more particularly
to methods of controlling the stripe height of magnetoresistive
devices in magnetic read/write heads.
[0003] 2. Description of the Related Art
[0004] Magnetic storage tape continues to be an efficient and
effective medium for data storage in computer systems. Increased
data storage capacity and retrieval performance is desired of all
commercially viable mass storage devices and media. In the case of
linear tape recording, a popular trend is toward multi-head,
multi-channel fixed head structures with narrowed recording gaps
and data track widths so that many linear data tracks may be
achieved on a tape medium of a predetermined width, such as
one-half inch width tape. To increase the storage density of
magnetic tapes and storage systems, transducer elements, e.g.,
magnetoresistive (MR) elements or devices, on the head and data
tracks on the tape are arranged with greater density.
[0005] Magnetic tape heads typically include an active device
region including raised strips or ridges, commonly referred to as
islands, bumps, or rails, that provide a raised tape support or
wear surface across which the magnetic tape advances. One or more
of these raised islands includes embedded data transducers. The
embedded transducers can be either a recording device for writing
information to a magnetic tape or a reproducing device for reading
information from a magnetic tape. An embedded recording device
produces a magnetic field in the vicinity of a small gap in the
core of the device, which causes information to be stored on a
magnetic tape as the tape advances across the support surface. In
contrast, a reproducing device detects a magnetic field from the
surface of a magnetic tape as the tape advances over the support
surface. Additionally, raised islands may be included without
transducers to help support and guide the magnetic tape over the
head, generally referred to as outriggers.
[0006] Typically, a plurality of embedded transducers are spaced
transversely across a direction of tape transport. The transducers
may be sized and disposed along an island for varying storage tape
data formats, e.g., different numbers of channels, track widths,
and track densities. For example, a four channel head includes four
read and four write transducers spaced transversely across a tape
path. The width of the read/write transducers and the distance
between adjacent read/write transducers is associated with the
density of tracks to be written to and read from the storage tape.
Storage capacity of magnetic tapes are generally increased with the
use of smaller more closely positioned read/write transducers in
the tape head.
[0007] As the storage tape and tape drive industry evolves and
achieves increases in storage capacity, the tape head and media
designs continue to make changes from one generation to the next.
For instance, new data formats with more densely positioned
read/write transducer elements on tape heads, more densely
positioned tracks on the storage tape, and thinner storage tape
increases the storage capacity of storage tape devices. For
example, to increase storage capacity of storage tape, the storage
tape may be thinned, e.g., lower magnetization thickness (Mrt),
while narrowing and thinning the MR devices in the head.
[0008] Typical MR devices for use with magnetic recording heads are
manufactured using standard semiconductor type processing methods.
For example, multiple rows of magnetic recording transducers are
deposited simultaneously on wafer substrates and cut into active
device regions for incorporation into a magnetic recording head.
After a section of magnetic recording transducers are cut from the
wafer, they are subject to a lapping process to reduce the stripe
heights of the MR devices to a desired height and smooth or polish
the surface of the structure. Stripe height is one of the key
parameters that control the signal output and device behavior of a
magnetoresistive recording head. The stripe height generally
determines the sensitivity of the magnetoresistive device to a
magnetic field, where a reduction in stripe height typically
produces a more sensitive magnetoresistive device. As magnetic
recording density increases, scaled down MR devices, e.g.,
anisotropic magnetoresistive (AMR) or giant magnetoresistive (GMR)
devices, are used to achieve adequate signal output. As MR devices
scale down, stripe height scales down accordingly.
[0009] The desire for shorter stripe height leads to a desire for
tighter control of stripe height during manufacturing, which is
generally accomplished by mechanical lapping using one or more
Electronic Lapping Guides (ELGs). It is generally unwise to use the
actual MR devices for monitoring stripe height because of the
potential for electrostatic discharge during the lapping process,
which may damage the device. In the manufacture of typical
multi-channel tape heads on a wafer, for example, a pair of ELGs is
disposed at each end of a cluster of MR devices. The ELGs are
monitored during manufacturing to determine the stripe height of
the active MR devices of the cluster. For example, the lapping
process is controlled to cease when the ELG resistance reaches a
calculated value associated with a desired stripe height of the MR
devices. The calculated ELG resistance, however, is subjected to
variations in the geometry and material thickness of the ELG
devices, which may result in large cluster-to-cluster stripe height
variations.
[0010] It is desired to provide tighter control over stripe height
during manufacturing, e.g., to provide smaller stripe heights and
more densely configured magnetoresistive devices for recording
heads.
BRIEF SUMMARY
[0011] In one aspect, a method for manufacturing a magnetic
read/write head is provided. In one example, the method includes
forming a plurality of magnetoresistive devices, a reference
device, and a monitoring device, where the reference device
includes a stripe height less than the plurality of
magnetoresistive devices and monitoring device. Material is removed
from an air bearing or tape bearing surface, e.g., by lapping,
thereby reducing the stripe height of the magnetoresistive devices
and monitoring device. A characteristic of the reference device,
e.g., resistance, voltage, or the like, is compared with a
characteristic of the monitoring device, wherein the characteristic
of the monitoring device varies as material is removed from the
surface. Material may be removed from the surface until the
characteristic of the monitoring device and the reference device
are substantially equal, at which time, the stripe height of the
monitoring device and magnetoresistive devices are substantially
equal to that of the reference device.
[0012] The reference device may be formed with a desired stripe
height of the magnetoresistive devices and serve as a proxy for the
stripe height of the magnetoresistive devices. The reference device
and monitoring device may be formed on the same level and through
the same processing steps as readers of the magnetoresistive
devices, thereby reducing differences with different processing
levels and steps. The reference device and monitoring device may be
placed adjacent the plurality of magnetoresistive devices to
further enhance control over stripe height. Further, a set of
devices including a reference device and monitoring device may be
included on opposite sides of each plaster of magnetoresistive
devices to reduce device-to-device variations across a cluster.
[0013] In another example, a method for manufacturing a magnetic
head includes forming a plurality of magnetoresistive devices, a
reference device, and a monitoring device on a substrate, wherein
the magnetoresistive devices and the monitoring device are formed
in the same manner, and the reference device is formed having a
stripe height less than the magnetoresistive devices. The method
further includes a measuring an electrical characteristic of the
reference device and an electrical characteristic of the monitoring
device, and lapping a surface of the substrate including the
magnetoresistive devices, the monitoring device, and the reference
device until the electrical characteristic of the reference device
and the electrical characteristic of the monitoring device are
equal or within desired tolerances.
[0014] According to another aspect, a magnetic recording head is
provided. In one example the magnetic recording head includes a
plurality of magnetoresistive devices, and a pair of electronic
lapping guides including a monitoring device and a reference
device, wherein the monitoring device and the reference device are
used during a lapping process to determine the relative height of
the reference device to the monitoring device.
[0015] Various aspects and examples are better understood upon
consideration of the detailed description below in conjunction with
the accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 illustrates an exemplary tape drive system;
[0017] FIG. 2 illustrates an exemplary magnetic recording head;
[0018] FIGS. 3A and 3B illustrate an exemplary configuration of MR
devices and ELGs;
[0019] FIGS. 4A-4C illustrate an exemplary configuration of MR
devices and ELGs (including a monitoring device and reference
device);
[0020] FIG. 5 illustrates an exemplary method for manufacturing a
magnetic recoding head including a monitoring device and reference
device; and
[0021] FIG. 6 illustrates another exemplary configuration of MR
devices and ELGs (including a monitoring device and a reference
device).
DETAILED DESCRIPTION
[0022] Exemplary methods for manufacturing magnetic recording heads
using a reference device and a monitoring device are provided. The
following description is presented to enable any person of ordinary
skill in the art to make and use the exemplary methods and
associated devices. Descriptions of specific materials, techniques,
and applications are provided only as examples. Various
modifications to the examples described herein will be readily
apparent to those of ordinary skill in the art, and the general
principles defined herein may be applied to other examples and
applications without departing from the spirit and scope of the
invention. Thus, the present invention and its various aspects are
not intended to be limited to the examples described and shown, but
is to be accorded the scope consistent with the appended
claims.
[0023] Scaled down MR devices or elements, e.g., AMR or GMR
devices, are desired for higher magnetic recording density. As MR
devices scale down, the stripe height of the MR devices is scaled
down accordingly. Conventional stripe height control using
mechanical lapping and calculated ELG resistance to stop lapping
often results in cluster-to-cluster stripe height variations.
Accordingly, exemplary methods described herein may provide
improved control over the stripe height of MR devices, thereby
allowing, for example, for the manufacture of smaller, more densely
positioned MR devices.
[0024] One exemplary manufacturing method for achieving improved
stripe height control in multi-channel magnetic read/write heads
includes manufacturing MR devices using a reference device and
monitoring device. The reference device is formed with a target
stripe height desired for the MR devices, and the monitoring device
is formed similarly to the MR devices (e.g., similar to a read
element of an active MR device). The monitoring device is monitored
during manufacturing, e.g., during a lapping or polishing step,
until resistance of the monitoring device equals the resistance of
the reference device.
[0025] In one example, the stripe height of the reference device is
determined by wafer processing, e.g., photolithographic wafer
processes. The reference device may be precisely manufactured with
desired stripe height characteristics using typical wafer
processing techniques such that a desired stripe height of the MR
devices, e.g., read and/or write elements, may be achieved by
measuring the reference device and monitoring device. In one
example, the reference device and monitoring device are
manufactured in the same manner, e.g., same processing level and
steps, as the read elements of the active MR devices, which may
reduce variations between the active MR devices and the reference
and monitoring devices. Additionally, in one example, the reference
device and monitoring device ate formed adjacent the MR devices to
reduce stripe height variations among them.
[0026] The following discussion describes examples as being
particularly useful as part of a linear tape drive system utilizing
magnetoresistive tape heads for performing read and write
operations on magnetic storage media (such as magnetic particle
tape). It will be understood, however, that the various examples
may be useful with other magnetic storage media and devices such as
hard disks, floppy disks, and the like. Accordingly, the exemplary
manufacturing methods and devices may be directed to and utilized
in various magnetic storage systems.
[0027] FIG. 1 illustrates a cut-a-way view of an exemplary magnetic
tape drive 10 in which exemplary tape heads as described herein may
be used. The particular arrangement of tape drive 10 is provided
for completeness of the operating environment for exemplary tape
heads and to facilitate description of how exemplary tape heads may
be utilized during operation of a tape drive. Tape drive 10
includes a tape cartridge 12 inserted into a receiver 14. Tape
drive 10 includes a motor (not shown) which drives a cartridge
supply reel 16 and moves tape 20 at a particular speed (e.g., 120
inches per second or more). Tape drive 10 may also include a second
motor (not shown) which drives a take-up reel 18. Tape 20 may be
driven in either a forward direction or a reverse direction to
write data onto or read data from the tape as controlled by a motor
controller circuit (not shown in FIG. 1, but typically provided on
one or more printed circuit boards). The controller may also be
adapted for controlling magnitudes of read/write currents passed
through head 30, e.g., to select particular read/write elements for
particular data formats and data tracks. Tape 20 is guided through
tape drive 10 by a plurality of tape guide assemblies 24-29 between
the take-up reel 18 and the cartridge 12 and past tape head 30.
[0028] FIG. 2 illustrates a perspective view of an exemplary tape
head 200 including raised elongated bumps or islands 220, 230, 240,
and 250, which may be used in a digital linear tape drive similar
to drive 10 of FIG. 1. Included along raised islands 220 and 230
are data transducers or read/write elements 224 (shown only along
island 220) arranged transversely to the direction of tape
transport to enable reading from and writing to tape 202.
Additionally, a monitoring device 210 and reference device 211 are
included adjacent read/write element 224, which were used during
manufacturing tape head 200 as described herein. As shown, tape
head 200 is adapted for contacting media, such as magnetic particle
tape 202 that typically has a width ranging from 5 to 20
millimeters.
[0029] The fabrication of exemplary tape heads having
magnetoresistive elements and including (and/or manufactured with)
ELGs may be manufactured utilizing any of a number of suitable
wafer/semiconductor processing techniques previously developed and
well known in the art. For example, thin-film heads, such as head
200 shown in FIG. 2, are fabricated in clean rooms using vacuum or
physical vapor deposition methods (such as RF or DC magnetron
sputtering, RF or DC diode sputtering, RF or DC triode sputtering)
and ion beam deposition, batch photolithographic methods (such as
photoresist masking, coating, and developing), chemical assisted
and reactive ion-beam etching, photoresist stripping and etching
that allow for very small head and element dimensions and precise
positioning and alignment of multiple transducer elements (such as
elements 224). The slots or separation of the islands 220 and 240
can be achieved using laser trimming, precision grinding, or other
machining techniques. Each island, such as island 220 or 240, may
be fabricated by encapsulating layers of materials within two or
more substrate materials followed by lapping or fine polishing to
achieve a desired media contact contour and surface. Alternatively,
each island may be fabricated of several segments or portions that
are then epoxy-bonded together to create the elongated islands. The
media contact surface may be coated with a corrosion or wear
resistant thin layer to protect the read/write elements.
[0030] The resulting active island generally includes the
read/write elements and is made of thin layers of different
materials (such as metal alloys and insulating materials). The tape
head may be configured to be a thinfilm inductive head, a thinfilm
AMR head, a dual MR head, an integrated thinfilm inductive write
and MR or GMR read head, or other thinfilm head design.
Additionally, inactive islands or outriggers may be fabricated in a
similar fashion to the active islands using similar materials or
using different materials. Alternatively, inactive islands may be
bonded to the head and formed in differing thinfilm processes.
[0031] The number of thinfilm layers utilized in the read/write
elements and the make-up of each layer may be varied depending on
the particular application and design considerations. For example,
the read/write elements may be fabricated with insulating layers
(such as alumina) and top and bottom layers or magnetic poles of
cobalt-zirconium-tantalum (CZT), which is commonly used in thinfilm
heads and for which, manufacturing processes are well understood by
those of ordinary skill in the arts. Poles and shields fabricated
using at least one of cobalt, nickel, and iron are also useful for
fabricating read/write elements. The base substrate upon which the
read/write elements are built may be ferrite, aluminum oxide
titanium carbide (AlTiC) or other materials. The specific materials
or fabrication processes use to manufacture exemplary heads as
described herein are not limited to any specific materials or
fabrication processes.
[0032] FIGS. 3A and 3B illustrate top views of a conventional
configuration of ELGs 310, 312, and active MR devices 324 formed on
a surface of a suitable substrate. The design includes two pairs of
ELGs, each pair including a large ELG 310 and a small ELG 312. The
distance between active devices 324 and ELGs 310 and 312 is not to
scale and active devices 324 are typically separated from ELGs 310
and 312 by a distance ranging from 1 mm to 3.5 mm depending, for
example, on the number of channels in the tape head. It will be
understood that the figures include exemplary dimensions of active
devices and ELGs and these dimensions are illustrative only.
[0033] Initially, the large ELGs 310, small ELGs 312, and MR
devices 324 have a stripe height larger than desired, as shown in
FIG. 3B, extending from above or behind the zero stripe height line
("zero SH") corresponding to the active device 324 downward. One or
more lapping procedures are performed to wear down active devices
324 and remove material from the bearing surface (e.g., an air
bearing surface ("ABS") as referred to with respect to disk drive
heads, or the tape bearing surface ("TBS") as referred to with
respect to tape drive heads), thereby reducing the stripe height to
a desired stripe height, e.g., shown here as line Ls.
[0034] Generally, large ELGs 310 are used to balance the initial
lapping (or rough lapping) of the structure to level the surface
for subsequent lapping processes. Small ELGs 312 are then used as
monitoring devices in the final lapping (or polishing) to reduce
the stripe height of MR device 324 to a desired stripe height, for
example, 1.0 .mu.m or less. In particular, the resistance of small
ELGs 312 are monitored and compared to predetermined or calculated
ELG resistance values to determine sufficient lapping, i.e., when
to stop the lapping process for a particular stripe height of MR
devices 324.
[0035] As described above, however, relying on calculated ELG
resistance values may lead to variation across different clusters.
The variance becomes increasingly problematic as the desired stripe
heights decrease. Further, each ELG 310, 312 is generally disposed
atop a baselayer, whereas the active devices are built atop CZT
bottom shield and read gap. Forming active devices 324 and ELGs
310, 312 on different levels may result in different critical
dimensions due to the nature of optical imaging (e.g., different
depths of focus over varying layers during photoresist processes
may result in different critical dimensions).
[0036] FIGS. 4A and 4B illustrate top views of an exemplary
configuration of active MR devices 424 and ELGs 410, 411, and 412.
In this example, the ELGs include at least one pair of devices, a
monitoring device 410 and reference device 411, located adjacent
active devices 424. Additionally, large ELG 412 may be included and
located at both ends of the cluster of active devices 424 to level
and smooth the surface in a rough polishing process similar to the
conventional configuration described.
[0037] In one example, reference device 411 and monitoring device
410 are produced by photolithographic wafer processing similar to
active devices 424. In particular, reference device 411 and
monitoring device 410 are formed to have the same structure as
active readers except for the wafer defined stripe height of
reference device 411. For example, reference device 411 and
monitoring device 410 may be formed on the same level and with the
same process steps as readers of active devices 424, thereby
reducing or eliminating the critical dimension differences
associated with different levels. Further, reference device 411 and
monitoring device 410 may be disposed adjacent each end of the
active device area, for example, at a pitch similar to active
devices 424. Reference device 411 is formed to have a stripe height
equal to that desired or targeted of active devices 424. In this
particular example, a stripe height of 1.0 .mu.m is shown for
illustrative purposes only. Monitoring device 410 is formed
similarly or identically to active devices 424 and includes an
initial stripe height greater than reference device 411 (in this
example greater than 1.0 .mu.m, and similar to the initial stripe
height of active devices 424). Accordingly, monitoring device 410
behaves similarly to an active reader during lapping processes.
Measurements of monitoring device 410 and reference device 411 may
be compared to determine relative stripe heights, where the height
of reference device 411 should approximate the stripe height of
active devices 424. Accordingly, monitoring device 410 may be
monitored during lapping and stopped using the wafer-defined
reference device 411.
[0038] In one exemplary lapping process using the configuration
shown in FIGS. 4A and 4B, initial lapping of the ABS/TBS is
performed using large ELGs 412 to balance the surface and reduce
large scale roughness. Thereafter, the lapping process is continued
while monitoring an electrical characteristic of reference device
411 and monitoring device 410, for example, monitoring the
resistance of each device 410 and 411. Removal of material from the
ABS/TBS is ceased when the stripe height of monitoring device 410
reaches a similar or identical height as reference device 411, as
indicated by the measured electrical characteristic. For example,
when resistance measurements of reference device 411 and monitoring
device 410 are equal or within desired tolerances, removal of the
surface should be stopped. In some examples, stripe heights may be
lapped to within 0.05 .mu.m using a monitoring device 410 and
reference device 411 as shown in FIGS. 4A-4C (in contrast with
about 0.2 .mu.m with ELGs 310 and 312 of FIGS. 3A and 3B, for
example). In some examples, additional polishing or conditioning of
the surface, which has little or no effect on stripe heights, may
be performed.
[0039] Reference device 411 is formed with a targeted stripe
heights pre-defined by the wafer processing. For illustrative
purposes only, a targeted 1 .mu.m stripe height is shown in FIG.
4B. In one example, the reference devices 411 and monitoring
devices 410 are built the same manner and at the same time as the
readers of active devices 424, e.g., using suitable wafer
processing methods known in the art. Accordingly, reference device
411 and monitoring device 410 provide an effective guide for
achieving desired stripe heights with reduced tolerances over
conventional methods. Additionally, the proximity of reference
device 411 and monitoring device 410 to active devices 424 may
increase the accuracy and control of the stripe heights. For
examples, exemplary guides such as reference device 411 and
monitoring device 410 have been shown to provide better than two
times improvement in cluster-to-cluster stripe height control of
active devices 424.
[0040] FIG. 4C illustrates the exemplary head after lapping active
devices 424 to a stripe height equal to reference device 411. The
cluster of active devices 424 may be cut from the substrate and
incorporated into a head structure similar to FIG. 2, for example.
In one example, monitoring device 410 and reference device 411
remain with active devices 424 after bar cut. In other examples,
reference device 411 and/or monitoring device 410 maybe cut from
the active device region after processing.
[0041] In one example, the trackwidth of monitoring device 410 and
reference device 411 are equal to or greater than the active
readers of active devices 424. This feature may minimize the impact
of gauging capability of instruments used in measuring electrical
characteristics of the monitoring device 410 and reference device
411. Readers of active devices 424 generally have relatively narrow
read trackwidths which often result in low MR resistance values.
For example, gauging sensitivity may by improved utilizing a 100
ohm resistor versus a 20 ohm resistor.
[0042] It is noted that various other configurations of reference
devices and monitoring devices may be utilized to improve
device-to-device stripe height uniformity. For example, any number
of reference devices and monitoring devices may be used for each
cluster of active devices. The reference and monitoring devices may
be disposed or intermixed within the active devices. Further, a
greater number of monitoring devices could be used than reference
devices, or vice versa.
[0043] FIG. 5 illustrates an exemplary lapping method using a
reference device and monitoring device as described herein, e.g.,
as shown in FIGS. 4A and 4B. In block 510 a wafer is processed to
form active devices, e.g., read/write MR devices arranged in one or
more clusters as described. Further, at least one pair of ELG
devices including a monitoring device and reference device is
formed. Additionally, the wafer may be processed to include
conventional ELGs, e.g., such as large and/or small ELGs as
described above. The wafer may be manufactured by any suitable
wafer processing methods known in the art.
[0044] In block 520, the wafer is polished to remove material from
the ABS/TBS of the substrate including the active devices and
monitoring device(s). A polishing process is performed, e.g., a
lapping process or the like, to remove material from the ABS/TBS
and grind the active devices to a desired stripe height as
described below. In one example, several polishing steps may be
used, e.g., a rough polish while monitoring conventional large
and/or small ELGs, if present, followed by a fine or smooth
polishing to reach a desired stripe height.
[0045] In block 530, the reference device and monitoring device are
monitored intermittently or continuously during the one or more
polishing steps of block 520. In particular, an electrical
characteristic, e.g., the resistance, voltage, or the like, of the
reference device and monitoring device are measured and compared.
In one example, a test signal is sent through the reference and
monitoring device to determine the relative stripe heights.
Material is removed from the ABS/TBS of the substrate until the
measured values from the reference device and monitoring device are
substantial equal, e.g., until the measured values indicate the
stripe heights are equal or within desired tolerances. When the
values are substantially equal, the polishing is ceased in block
540 thereby reducing the stripe height of the active devices to a
desired height predetermined by the reference device.
[0046] FIG. 6 illustrates a top view of another exemplary
configuration of active devices 624 and dual ELGs having a
monitoring device 610 and reference device 611. In this instance,
particularly suitable for use in a GMR magnetic head, for example,
front flux guides 634, 620, 621, and 622 are used with active
device 624, monitoring device 610, reference device 611, and large
ELG 612 respectively. Again, devices containing the wafer defined
stripe height and flux guide (in this illustrative example, 1.0
.mu.m and 0.2 .mu.m respectively) are used as references to stop
lapping and define the final stripe height of active devices 624.
Monitoring device 610 and reference device 611 are used in a
similar fashion as described above to polish the surface of the
substrate and control the stripe height of active devices 624.
[0047] The above detailed description is provided to illustrate
various examples and is not intended to be limiting. It will be
apparent to those skilled in the art that numerous modification and
variations within the scope of the present invention are possible.
For example, various configurations of active devices and
combinations of reference and monitoring devices may be used.
Further, numerous other materials and processes not explicitly
described herein may be used within the scope of the exemplary
methods and structures described as will be recognized by those of
ordinary skill in the art. Additionally, throughout this
description, particular examples have been discussed and how these
examples are thought to address certain disadvantages in related
art. This discussion is not meant, however, to restrict the various
examples to methods and/or systems that actually address or solve
the disadvantages. Accordingly, the present invention is defined by
the appended claims and should not be limited by the description
herein.
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