U.S. patent application number 10/811741 was filed with the patent office on 2004-09-16 for embedded lapping guide.
Invention is credited to Gibson, Charles A., Lam, Chuck Fai, Martin, Kenneth R..
Application Number | 20040179310 10/811741 |
Document ID | / |
Family ID | 26793081 |
Filed Date | 2004-09-16 |
United States Patent
Application |
20040179310 |
Kind Code |
A1 |
Lam, Chuck Fai ; et
al. |
September 16, 2004 |
Embedded lapping guide
Abstract
A magnetic head cluster is provided along with a method of
making a magnetic head cluster. The magnetic head cluster comprises
a substrate having a plurality of magnetoresistive (MR) read and
inductive magnetic write transducers and a plurality of terminals
formed thereon. A plurality of lapping guides are also provided on
the substrate between adjacent transducers.
Inventors: |
Lam, Chuck Fai; (Kowloon,
HK) ; Martin, Kenneth R.; (Palmer, MA) ;
Gibson, Charles A.; (Clinton, MA) |
Correspondence
Address: |
SIDLEY AUSTIN BROWN & WOOD LLP
717 NORTH HARWOOD
SUITE 3400
DALLAS
TX
75201
US
|
Family ID: |
26793081 |
Appl. No.: |
10/811741 |
Filed: |
March 29, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10811741 |
Mar 29, 2004 |
|
|
|
10097294 |
Mar 14, 2002 |
|
|
|
60276693 |
Mar 16, 2001 |
|
|
|
Current U.S.
Class: |
360/316 ;
29/603.1; G9B/5.052; G9B/5.078 |
Current CPC
Class: |
G11B 5/3116 20130101;
B24B 37/013 20130101; G11B 5/3103 20130101; G11B 5/3173 20130101;
B24B 49/04 20130101; B24B 37/048 20130101; Y10T 29/49037 20150115;
G11B 5/1871 20130101; G11B 5/3967 20130101; G11B 5/3948 20130101;
G11B 5/3166 20130101; B24B 49/10 20130101 |
Class at
Publication: |
360/316 ;
029/603.1 |
International
Class: |
G11B 005/39 |
Claims
What is claimed is:
1. A magnetic head cluster comprising: a substrate; at least two
transducer elements disposed on a surface of the substrate; and at
least one resistive element disposed on the surface of the
substrate between two of the at least two transducer elements.
2. A magnetic head cluster in accordance with claim 1, further
comprising a plurality of resistive elements, and wherein each of
the plurality of resistive elements is disposed on the surface of
the substrate between two of the at least two transducer
elements.
3. A magnetic head cluster in accordance with claim 2, wherein at
least one of the at least two transducer elements includes a
magnetoresistive read head and an inductive magnetic write
head.
4. A magnetic head cluster in accordance with claim 3, wherein at
least one of the plurality of resistive elements is an analog
switch lapping guide.
5. A magnetic head cluster in accordance with claim 4, wherein at
least one of the plurality of resistive elements is a digital
switch lapping guide.
6. A magnetic head cluster in accordance with claim 3, wherein at
least one of the plurality of resistive elements is a digital
switch lapping guide.
7. A magnetic head cluster in accordance with claim 3, further
comprising at least one terminal disposed on the surface of the
substrate.
8. A magnetic head cluster in accordance with claim 2, wherein at
least one of the at least two transducer elements includes a read
head selected from a group consisting of anisotropic
magnetoresistive read heads, giant magnetoresistive read heads, and
spin valve read heads.
9. A magnetic head cluster comprising: a substrate having a surface
and a plurality of edge portions; at least two transducer elements
disposed on the surface of the substrate, each of the at least two
transducer elements being adjacent to at least one of the plurality
of edge portions; and at least one resistive element disposed on
the surface of the substrate, wherein none of the at least one
resistive elements are positioned between any one of the at least
two transducer elements and a respective adjacent edge portion.
10. A magnetic head cluster in accordance with claim 9, wherein at
least one of the at least two transducer elements includes a read
head selected from a group consisting of anisotropic
magnetoresistive read heads, giant magnetoresistive read heads, and
spin valve read heads.
11. A magnetic head cluster in accordance with claim 10, wherein at
least one of the plurality of resistive elements is selected from a
group consisting of analog switch lapping guides and digital switch
lapping guides.
12. A magnetic head cluster in accordance with claim 11, further
comprising at least one terminal disposed on the surface of the
substrate.
13. A magnetic head cluster in accordance with claim 9, wherein at
least one of the at least two transducer elements includes a
magnetoresistive read head and an inductive magnetic write
head.
14. A method of fabricating a magnetic head cluster comprising the
steps of: providing a substrate; forming at least two transducer
elements on a surface of the substrate; and forming at least one
resistive element on the surface of the substrate between two of
the at least two transducer elements.
15. A method of fabricating a magnetic head cluster in accordance
with claim 14, further comprising the step lapping an edge portion
of the magnetic head cluster.
16. A method of fabricating a magnetic head cluster in accordance
with claim 15, further comprising the step of measuring the
resistance of the at least one resistive element.
17. A method of fabricating a magnetic head cluster in accordance
with claim 16, wherein the step of measuring the resistance is
performed during the step of lapping, and wherein the step of
lapping is performed until the resistance of at least one of the
resistive elements reaches a specified resistance.
18. A method of fabricating a magnetic head cluster in accordance
with claim 15, further comprising a plurality of resistive
elements, and wherein each of the plurality of resistive elements
is formed on the surface of the substrate between two of the at
least two transducer elements.
19. A method of fabricating a magnetic head cluster in accordance
with claim 18, further comprising the step of measuring the
resistance of at least one of the plurality of resistive
elements.
20. A method of fabricating a magnetic head cluster in accordance
with claim 19, wherein the step of measuring the resistance is
performed during the step of lapping, and wherein the step of
lapping is performed until the resistance of at least one of the
resistive elements reaches a predetermined resistance.
21. A method of fabricating a magnetic head cluster in accordance
with claim 15, wherein at least one of the plurality of resistive
elements is selected from a group consisting of analog switch
lapping guides and digital switch lapping guides.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/276,693, filed on Mar. 16, 2001, the entire
contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a magnetic head cluster for
a data storage device having read/write transducers, which are used
for communicating with a magnetic recording medium, and lapping
guides, which are used during lapping processes while fabricating
the magnetic head cluster. Further, the present invention relates
to a method for making a magnetic head cluster.
BACKGROUND OF THE INVENTION
[0003] Thin film magnetoresistive (MR) read and inductive write
transducers are widely used for magnetic heads in data storage
devices, such as disk drives and linear tape drives. Various types
of MR read heads are known in the art, including anisotropic
magnetoresistive (AMR) read heads, giant magnetoresistive (GMR)
read heads, and spin valve read heads. In typical magnetic tape
read/write heads, multiple merged MR read/inductive write
transducers are grouped into a single structure called a magnetic
head cluster. Each of the transducers is typically aligned in the
cluster along one edge, known as an air bearing surface (ABS) in
disk drive technology and known as a tape bearing surface (TBS) for
tape drives (for simplicity this surface will be referred to herein
as a tape bearing surface), which faces a recording medium during
normal read/write operation. In general, each transducer of a
cluster provides an unique read/write channel.
[0004] The demand for data storage has been increasing in recent
years and this demand has put pressure on fabrication processes for
more efficient and cost effective methods and devices. In order to
keep up with this demand, attempts to improve various aspects of
magnetic head technology include increasing the sensitivity of the
magnetic heads, reducing manufacturing costs, and simplifying
manufacturing processes.
[0005] A conventional manufacturing process for fabricating a
magnetic head cluster will be described next with reference to
FIGS. 1 and 2. As shown in FIGS. 1 and 2, a magnetic head cluster
115 is made by forming a plurality of inner merged MR
read/inductive write transducers 100 and outermost merged MR
read/inductive write transducers 105, a plurality of electrical
lapping guides 175, and a plurality of terminals 107 on a single
wafer 110. The wafer 110 can be formed from any material which has
high wear resistance, strength, fracture toughness, and good
electrical conductivity, such as an alumina titanium-carbide
(Al.sub.2O.sub.3/TiC) ceramic wafer. The processes used to form the
transducers 100 and 105 on the wafer 110 typically include a
combination of lithography, deposition (vacuum or plating), and
etching steps, all of which are known in the art. The transducers
100 and 105 are grouped into the clusters 115, which are separated
from one another by separation kerfs 120. As shown in FIG. 1, the
clusters 115 are aligned in rows and columns defined by the
separation kerfs 120. Once the process of forming the clusters 115
is complete, the wafer 110 is cut along the separation kerfs 120,
dividing the wafer 110 into a plurality of clusters. This
well-known process of cutting the wafer along the kerfs is commonly
referred to as "dicing."
[0006] As mentioned above, the transducers 100 and 105 included in
each cluster 115 are typically merged MR read/inductive write
transducers. As shown in FIG. 3, a conventional MR read transducer
125 typically includes an MR stripe 130, which exhibits variations
in resistance when exposed to a magnetic field. The stripe height
SH of the MR stripe 130 must be controlled within a tight
tolerance, such as within a few micro-inches, so that a sensed
magnetic signal can generate an optimum change in a resistance of
the MR stripe 130. The inductive write transducer 135 typically
comprises various layers of poles 140 and insulating material 145,
and also includes an electrical coil 150. The region of the
inductive write transducer 135 closest to an upper edge 155 (shown
on FIG. 2) of the cluster 115, where the two poles are separated
only by a thin insulating layer, is typically called a throat 160.
As will be explained later, the region closest to the upper edge
155 will eventually be lapped to form a tape bearing surface. As is
known in the art, the throat height TH must also be controlled
within a tight tolerance for the transducer to generate an optimum
magnetic signal.
[0007] When the separation kerfs 120 are formed on the wafer 110, a
slight amount of excess substrate is provided along the upper edge
155 of each cluster. The reason for providing this slight amount of
excess substrate is that the dicing process is not precise enough
to achieve the optimum stripe height SH and throat height TH for
each transducer 100 and 105. So, rather than inadvertently cutting
the stripe 130 or throat 160 too short while dicing the wafer 110,
the stripe 130 and throat 160 are intentionally left too long and
later are carefully shortened by a process known as lapping.
[0008] FIG. 4 shows an exaggerated view of the conventional lapping
process in order to provide a clear illustration. The broken line
in FIG. 4 represents a portion of the cluster 115 which has already
been removed by the lapping process. In FIG. 4, a controller 185
operates to activate and halt a lapping plate rotator 190. The
lapping plate rotator 190, when activated, causes a lapping plate
165 to rotate relative to the cluster 115, thereby grinding the
upper edge 155. Eventually, a sufficient amount of upper edge 155
is ground away to form a tape bearing surface 170. The tape bearing
surface 170 is a surface of the magnetic head cluster 115 which
will face a recording medium (not shown) when the magnetic head
cluster 115 is used for read/write operations. A lapping plate
pressure applicator 195 also receives signals from the controller
185 for continuously adjusting the amount of pressure being applied
to the cluster 115 during the lapping process. The lapping plate
pressure applicator 195 may include, for example, one or more dual
action air cylinders (not shown) for applying varying amounts of
pressure to different points on the cluster 115 in order to provide
for skew control. The controller 185 senses an electrical
resistance of the electrical lapping guides 175, which changes as
portions of the electrical lapping guides 175 adjoining the upper
edge 155 are ground away. The lapping process is complete once the
portions of the cluster 115 are removed up to line A, which
indicates the desired position of the tape bearing surface 170 of
the cluster 115.
[0009] During the lapping process, the excess portion of the
substrate 210 is carefully ground away by introducing an abrasive
material, such as a diamond slurry (not shown), between the
rotating lapping plate 165 and the upper edge 155 of the fixed
cluster 115. In order to provide for precise control during the
lapping process, the electrical lapping guides 175 are typically
provided between each outermost transducer 105 and a respective
outer edge 180 of each cluster 115. Once the electrical lapping
guides 175 reach a predetermined resistance, the controller 185
halts the motion of the lapping plate 165. Ideally, the
predetermined resistance is selected so that the target stripe
height SH and throat height TH are achieved.
[0010] In general, lapping guides and separation kerfs, which are
useful during the manufacturing of magnetic head clusters, have no
functional purpose during normal operation of a magnetic head
cluster. As mentioned above, electrical lapping guides are
typically provided between an outermost transducer and an outer
edge of each cluster. Thus, the size of each cluster is larger than
its functional size, which need only include transducers.
Therefore, from a functional standpoint, the wafer space occupied
by lapping guides and separation kerfs is wasted. Moreover, in
order to minimize the unit cost per cluster, efficient use of wafer
space is important. For this reason, recent efforts have been made
to increase the efficiency with which wafer space is utilized by
reducing the amount of wafer space used for lapping guides and
separation kerfs. Accordingly, separation kerfs have been reduced
to a very small size so that more clusters can be put onto the same
wafer.
[0011] U.S. Pat. No. 6,027,397 discloses further efforts to
efficiently utilize wafer space, wherein the cluster size is
reduced by putting the lapping guides onto the separation kerfs.
U.S. Pat. No. 5,588,199 discloses another attempt to efficiently
utilize wafer space, wherein the number of transducers per wafer is
increased by adding a resistor network, which is used as a lapping
guide, inside the transducers. Therefore, there is no need for a
separate electrical lapping guide. A similar approach can be found
in U.S. Pat. No. 5,772,493 by using an external magnetic excitation
field to the transducer and measuring the resistance of the MR
element in response to variations in the applied magnetic
excitation field.
[0012] Despite these past attempts to increase the efficiency with
which wafer space is utilized, there continues to be a need to
improve wafer utilization and simplify manufacturing processes.
BRIEF SUMMARY OF THE INVENTION
[0013] In view of the above shortcomings with the prior art, an
object of the present invention is to provide a magnetic head
cluster that includes lapping guides arranged in such a way so as
to reduce cluster size allowing for more clusters per wafer.
[0014] Another object of the present invention is to provide a
method of making a magnetic head cluster which allows for a reduced
cluster size so that more clusters per wafer may be formed.
[0015] In order to achieve the above objects, a magnetic head
cluster is provided that comprises a substrate having a surface
with at least two transducer elements disposed thereon and at least
one resistive element that is disposed between any two of the at
least two transducer elements.
[0016] In accordance with another aspect of the present invention,
a method of fabricating a magnetic head cluster having an edge
portion is provided that comprises the steps of providing a
substrate having a surface, forming at least two transducer
elements on the surface, forming at least one resistive element on
the surface between any two of the at least two transducer
elements, and lapping the edge portion of the magnetic head
cluster.
[0017] Depending on the design of the lapping processes, each
cluster can contain one or more electrical lapping guides. Such
lapping guides can be any combination of analog and/or digital
"switch" types that are well-known in the field.
[0018] In accordance with the present invention, the size of
electrical lapping guides can be reduced and the electrical lapping
guides can be positioned between the transducers so that the size
of the magnetic head cluster can be reduced to its functional size.
As a result, the total number of clusters that can be produced on a
wafer is increased.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The present invention is illustrated by way of example and
not limited in the figures of the accompanying drawings, in which
like reference numbers indicate similar parts:
[0020] FIG. 1 is a plan view of a wafer containing a plurality of
conventional magnetic head clusters formed in rows and columns;
[0021] FIG. 2 is a plan view of a conventional magnetic head
cluster;
[0022] FIG. 3 is a cross sectional view of a magnetoresistive (MR)
read and inductive write transducer 100 taken along line III-III of
FIG. 2;
[0023] FIG. 4 is a plan view of a lapping system for a conventional
cluster;
[0024] FIG. 5 is a plan view of a magnetic head cluster in
accordance with the present invention; and
[0025] FIG. 6 is a plan view of a lapping process in accordance
with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] FIG. 5 shows a preferred embodiment of the present
invention. A magnetic head cluster 315 of the present invention
includes a plurality of inner merged MR read/inductive write
transducers 300 and outermost merged MR read/inductive write
transducers 305, a plurality of electrical lapping guides 375, and
a plurality of terminals 307 formed on a substrate 410. The
substrate 410 can be a portion of a wafer (not shown) formed from
any material which has high wear resistance, strength, fracture
toughness, and good electrical conductivity, such as an alumina
titanium-carbide (Al.sub.2O.sub.3/TiC) ceramic wafer. The
transducers 300 and 305, lapping guides 375, and terminals 307 can
be formed on the substrate 410 by any of the known
transducer-forming processes.
[0027] The transducers 300 and 305 are preferably MR read and
inductive write transducers as discussed above, and can include any
combination of AMR, GMR, and spin valve read heads. The electrical
lapping guides 375 may be composed of any type of electrically
resistive material, including any combination of analog and/or
digital switch types that are well-known in the art. The terminals
307 can be composed of any type of electrically conductive
material, such as plated gold, suitable for transferring electrical
signals between the transducers 300 and 305 and an external
interface (not shown).
[0028] As shown in FIG. 5, the electrical lapping guides 375 are
each provided between adjacent inner transducers 300 and/or between
adjacent inner transducers 300 and outermost transducers 305. In
other words, in this preferred embodiment, there are no lapping
guides 375 provided between an outermost transducer 305 and an
adjacent outer edge 380 of the cluster 315. Compared to the
conventional magnetic head cluster 115 shown in FIG. 2, the
magnetic head cluster 315 is reduced in size since an excess amount
of the substrate 410 is not required to accommodate electrical
lapping guides 375 beyond the outermost transducers 305. Thus, the
cluster 315 is reduced to its actual functional size, allowing for
more clusters 315 to be formed on a wafer.
[0029] The transducers 300 and 305 included in the cluster 315 are
preferably merged inductive write and MR read transducers. The
transducers 300 and 305 can have the same configuration as the
conventional transducer 100, which is shown in FIG. 3. As shown in
FIG. 3, an MR read transducer 125 includes an MR stripe 130, which
experiences variations in resistance when exposed to a magnetic
field. The stripe height SH of the MR stripe 130 must be controlled
within a tight tolerance, such as within a few micro-inches, so
that a sensed magnetic signal can generate an optimum change in a
resistance of the MR stripe 130. The inductive write transducer 135
comprises various layers of poles 140, and insulating material 145,
and also includes an electrical coil 150. The region of the
inductive write transducer 135 closest to an upper edge 355 of the
cluster 315, where the two poles are separated only by a thin
insulating layer, is typically called a throat 160. As will be
explained later, the region closest to the upper edge 355 will
eventually be lapped to form a tape bearing surface. As is known in
the art, the throat height TH must also be controlled within a
similarly tight tolerance for the transducer to generate an optimum
magnetic signal.
[0030] FIG. 6 shows an exaggerated view of a lapping process in
accordance with the present invention in order to provide a clear
illustration. The broken line in FIG. 6 represents a portion of the
cluster 315 which has already been removed by the lapping process.
In FIG. 6, a controller 385 operates to activate and halt a lapping
plate rotator 390. The lapping plate rotator 390, when activated,
causes the lapping plate 365 to rotate relative to the cluster 315,
thereby grinding the upper edge 355. Eventually, a sufficient
amount of upper edge 355 is ground away to form a tape bearing
surface 370. The tape bearing surface 370 is a surface of the
magnetic head cluster 315 which will face a recording medium (not
shown) when the magnetic head cluster 315 is used for read/write
operations. A lapping plate pressure applicator 395 also receives
signals from the controller 385 for continuously adjusting the
amount of pressure being applied to the cluster 315 during the
lapping process. The lapping plate pressure applicator 395 may
include, for example, one or more dual action air cylinders (not
shown) for applying varying amounts of pressure to different points
on the cluster 315 in order to provide for skew control. The
controller 385 senses an electrical resistance of the electrical
lapping guides 375, which changes as portions of the electrical
lapping guides 375 adjoining the upper edge 355 are lapped away.
The lapping process is complete once the portions of the cluster
315 are removed up to line A, which indicates the desired position
of a tape bearing surface 370 of the cluster 315.
[0031] During the lapping process, an excess portion of substrate
410 is carefully ground away from the magnetic head cluster 315 by
introducing an abrasive material, such as a diamond slurry (not
shown), between a lapping plate 365 and an upper edge 355 of the
cluster 315. In order to provide for precise control during the
lapping process, a plurality of electrical lapping guides 375 are
provided between selected ones of the plurality of transducers 300
and 305. Once the electrical lapping guides 375 reach a
predetermined resistance, the controller 385 halts the motion of
the lapping plate 365. Ideally, the predetermined resistance is
selected so that the target stripe height SH and throat height TH
are achieved.
[0032] Although the present invention has been fully described by
way of preferred embodiments and methods, one skilled in the art
will appreciate that other embodiments and methods are possible
without departing from the spirit and scope of the present
invention.
* * * * *