U.S. patent application number 09/497756 was filed with the patent office on 2002-01-03 for method of manufacturing lapping control sensor for magnetoresistive effect head.
Invention is credited to Fukuroi, Osamu, Nakagawa, Yoshiro.
Application Number | 20020001671 09/497756 |
Document ID | / |
Family ID | 16813752 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020001671 |
Kind Code |
A1 |
Fukuroi, Osamu ; et
al. |
January 3, 2002 |
Method of manufacturing lapping control sensor for magnetoresistive
effect head
Abstract
A lapping control sensor for a MR head includes a multi-layered
structure of a metallic layer, an insulation layer, a resister
layer and a lead conductor layer, and being provided in parallel
with the MR head which has a multi-layered structure of at least a
lower shield layer, a shield gap insulation layer, a MR layer and a
lead conductor layer is provided. The insulation layer of the
lapping control sensor has a thickness larger than that of the
shield gap insulation layer of the MR head. The thickness of the
insulation layer of the sensor is 0.1 .mu.m or more.
Inventors: |
Fukuroi, Osamu; (Tokyo,
JP) ; Nakagawa, Yoshiro; (Tokyo, JP) |
Correspondence
Address: |
Arent Fox Kintner Plotkin & Kahn PLLC
Washington Square
Suite 600
1050 Connecticut Avenue NW
Washington
DC
20036-5339
US
|
Family ID: |
16813752 |
Appl. No.: |
09/497756 |
Filed: |
February 4, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09497756 |
Feb 4, 2000 |
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09130446 |
Aug 6, 1998 |
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6083081 |
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Current U.S.
Class: |
427/131 ;
G9B/5.116 |
Current CPC
Class: |
G11B 5/3163 20130101;
B24B 37/04 20130101; Y10T 29/49044 20150115; B24B 49/10 20130101;
Y10T 29/49021 20150115; Y10T 29/49032 20150115; G11B 5/1871
20130101; G11B 5/3116 20130101; G01B 7/10 20130101; Y10T 29/49043
20150115; G11B 5/3903 20130101 |
Class at
Publication: |
427/131 |
International
Class: |
B05D 005/12 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 1997 |
JP |
224436-1997 |
Claims
What is claimed is:
1. A lapping control sensor for a magnetoresistive effect head,
said sensor including a multi-layered structure of a metallic
layer, an insulation layer, a resister layer and a lead conductor
layer, and being provided in parallel with the magnetoresistive
effect head which has a multi-layered structure of at least a lower
shield layer, a shield gap insulation layer, a magnetoresistive
effect layer and a lead conductor layer, said insulation layer of
said lapping control sensor having a thickness larger than that of
said shield gap insulation layer of said magnetoresistive effect
head, the thickness of said insulation layer of said sensor being
0.1 .mu.m or more.
2. The sensor as claimed in claim 1, wherein said sensor is located
near said magnetoresistive effect head.
3. A lapping control sensor for a magnetoresistive effect head,
said sensor including a multi-layered structure of a metallic
layer, an insulation layer, a resister layer and a lead conductor
layer, and being provided in parallel with the magnetoresistive
effect head which has a multi-layered structure of at least a lower
shield layer, a shield gap insulation layer, a magnetoresistive
effect layer and a lead conductor layer, said metallic layer, said
insulation layer, said resister layer and said lead conductor layer
of said sensor being made of the same material as that of said
lower shield layer, said shield gap insulation layer, said
magnetoresistive effect layer and said lead conductor layer of said
magnetoresistive effect head, respectively, said insulation layer
of said lapping control sensor having a thickness larger than that
of said shield gap insulation layer, the thickness of said
insulation layer of said sensor being 0.1 .mu.m or more.
4. The sensor as claimed in claim 3, wherein said sensor is located
near said magnetoresistive effect head.
5. A lapping control method using the sensor as claimed in claim 1,
wherein the lapping control of a height of said magnetoresistive
effect layer of said magnetoresistive effect head is executed in
response to a signal from said lapping control sensor.
6. A lapping control method using the sensor as claimed in claim 3,
wherein the lapping control of a height of said magnetoresistive
effect layer of said magnetoresistive effect head is executed in
response to a signal from said lapping control sensor.
7. A method for manufacturing a lapping control sensor comprising
the steps of: sequentially depositing a metallic layer and an
insulation layer at a position in parallel with a magnetoresistive
effect head during depositing steps of a lower shield layer and a
shield gap insulation layer of said magnetoresistive effect head,
said insulation layer of said sensor having a thickness larger than
that of said shield gap insulation layer, the thickness of said
insulation layer of said sensor being 0.1 .mu.m or more; and
sequentially depositing a resistor layer and a lead conductor layer
on said insulation layer during depositing steps of a
magnetoresistive effect layer and a lead conductor layer of said
magnetoresistive effect head.
8. The method as claimed in claim 7, wherein said metallic layer,
said insulation layer, said resister layer and said lead conductor
layer of said sensor are made of the same material as that of said
lower shield layer, said shield gap insulation layer, said
magnetoresistive effect layer and said lead conductor layer of said
magnetoresistive effect head, respectively.
9. The method as claimed in claim 7, wherein said sensor is formed
to locate near said magnetoresistive effect head.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a lapping control sensor
used in controlling a height of a magnetoresistive effect (MR) head
(MR height) when the MR head is fabricated, to a lapping control
method using the sensor and to a manufacturing method of the
sensor.
DESCRIPTION OF THE RELATED ART
[0002] The MR height of a plurality of MR heads is collectively
controlled by lapping one surface (ABS, Air Bearing Surface) of
each bar obtained by cutting each row from a wafer so that the
plurality of MR heads are aliened in one row. To control the mutual
MR height of the plurality of MR heads of a bar and the mutual MR
height of the MR heads of a plurality of bars to a corrective
value, there are usually provided a plurality of lapping control
sensors called as an electric lapping guide (ELG) or a resistance
lapping guide (RLG) which detects the height of a lapped ABS
surface, in each bar. The lapping of the ABS surface can be
controlled in response to electric signals from the ELGs or
RLGs.
[0003] Each of the ELGs or RLGs is mainly composed of a resister
which is adjacent to the ABS surface to be lapped and extends in
parallel. The ELG or RLG teaches an amount of lapping by changing
its terminal voltage or its resistance due to the reduction of the
height of the resister polished with polishing of the MR height.
Such ELG with respect to the throat height of a magnetic pole gap
in an inductive head, not to the MR height, is known by, for
example, U.S. Pat. No. 4,689,877 and Japanese Unexamined Patent
Publication No. 63(1988)-191570.
[0004] In manufacturing the MR head, the ELG or RLG is generally
formed in the same process of manufacturing the MR head so as to
have the same layered structure as that of the MR head. FIG. 1
shows a multi-layered structure of a conventional ELG or RLG. As
shown in the figure, the conventional ELG or RLG has a
multi-layered structure consisting of a metallic layer (shield
layer) 10, an insulation layer (shield gap layer) 11, a resister
layer (MR layer) 12 and lead conductors 13 and 14, which are made
of the same material and layer thickness as those of the MR
head.
[0005] Recently, in order to increase the bit density in a magnetic
disk unit, narrower gap of the MR shield has been demanded. In
order to make the shield gap narrower, it is necessary to decrease
the thickness of the MR layer and/or the thickness of the shield
gap insulation layer. However, there is a limit in decreasing the
layer thickness of the MR layer because the characteristics of the
head will be deteriorate. Thus, the thickness of the shield gap
insulation layer sandwiching this MR layer has to be decreased.
When the thickness of the shield gap insulation layer in the MR
head is decreased, thickness of the insulation layer 11 in the ELG
or RLG is also decreased as well.
[0006] When the thickness of the insulation layer 11 of the ELG or
RLG is decreased as mentioned above, a short circuit may be formed
temporarily between the lead conductors 13 and 14 via the metallic
layer 10 and smears 15 (burrs) which may be protruded from the
metallic layer 10 during the lapping control of the MR height. The
smear metals 15 produced on the lapped surface of the metallic
layer 10 are extended across the insulation layer 11 to contact the
lead conductors 13 and 14 when the lapping direction is a direction
of an arrow shown in FIG. 1, resulting in forming the electric
short circuit between the metallic layer 11 and the lead conductors
13 and 14. When the short circuit is formed, resistance between the
terminals of lead conductors 13 and 14, which is an ELG or RLG
detecting output, is temporarily decreased and generates many
noises in signals, resulting in that lapping for controlling of the
MR height cannot be carried out.
[0007] In order to prevent the production of metallic smears when
lapping the metallic layer, it may be considered to provide no
metallic layer as an under layer of the ELG or RLG. However, if the
resistor layer of the ELG or RLG has no under layer, it cannot have
the same resistive change characteristics as the MR layer of the MR
head due to differences between surface characteristics such as
unevenness of the under layer. In order to enhance the
controllability of the MR height, it is desirable that the resistor
layer of the ELG or RLG and the MR layer of the MR element have the
same resistive change characteristics.
[0008] In order to prevent the production of metallic smears when
lapping the metallic layer, it is also considered that a lapping
direction is set in the opposite direction to the direction of the
arrow in FIG. 1. However, when the lapping direction is reversed, a
recession between a substrate (slider) and an under film formed
thereon becomes remarkably large causing the characteristics of the
MR head itself to greatly deteriorate.
SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
provide a lapping control sensor which can securely and stably
control a MR height of a MR head to a correct value.
[0010] It is another object of the present invention to provide a
lapping control method using the sensor and a manufacturing method
of the sensor.
[0011] According to the present invention, a lapping control sensor
for a MR head, including a multi-layered structure of a metallic
layer, an insulation layer, a resister layer and a lead conductor
layer, and being provided in parallel with the MR head which has a
multi-layered structure of at least a lower shield layer, a shield
gap insulation layer, a MR layer and a lead conductor layer is
provided. The insulation layer of the lapping control sensor has a
thickness larger than that of the shield gap insulation layer of
the MR head. The thickness of the insulation layer of the sensor is
0.1 .mu.m or more.
[0012] Also, according to the present invention, a lapping control
sensor for a MR head, including a multi-layered structure of a
metallic layer, an insulation layer, a resister layer and a lead
conductor layer, and being provided in parallel with the MR head
which has a multi-layered structure of at least a lower shield
layer, a shield gap insulation layer, a MR layer and a lead
conductor layer. The metallic layer, the insulation layer, the
resister layer and the lead conductor layer of the sensor are made
of the same material as that of the lower shield layer, the shield
gap insulation layer, the MR layer and the lead conductor layer of
the MR head, respectively. The insulation layer of the lapping
control sensor has a thickness larger than that of the shield gap
insulation layer. The thickness of the insulation layer of the
sensor is 0.1 .mu.m or more.
[0013] Since an insulation layer of the lapping control sensor is
formed so as to have a thickness of 0.1 .mu.m or more which is
thicker than the thickness of a shield gap insulation layer of the
MR head, noise generation due to the metallic smears can be
prevented. Accordingly, the MR height can be securely and stably
controlled to a correct value.
[0014] According to the present invention, furthermore, a lapping
control method using the above-mentioned sensor is provided. In
this method, the lapping control of a height of the MR layer of the
MR head is executed in response to a signal from the lapping
control sensor.
[0015] According to the present invention, also, a method for
manufacturing a lapping control sensor is provided. This method
includes the steps of sequentially depositing a metallic layer and
an insulation layer at a position in parallel with a MR head during
depositing steps of a lower shield layer and a shield gap
insulation layer of the MR head, in which the insulation layer of
the sensor has a thickness larger than that of the shield gap
insulation layer and the thickness of the insulation layer of the
sensor is 0.1 .mu.m or more, and sequentially depositing a resistor
layer and a lead conductor layer on the insulation layer during
depositing steps of a MR layer and a lead conductor layer of the MR
head.
[0016] It is preferred that each of a plurality of lapping control
sensors is located near the respective MR heads.
[0017] It is also preferred that the metallic layer, the insulation
layer, the resister layer and the lead conductor layer of the
sensor are made of the same material as that of the lower shield
layer, the shield gap insulation layer, the MR layer and the lead
conductor layer of the MR head, respectively.
[0018] Further objects and advantages of the present invention will
be apparent from the following description of the preferred
embodiments of the invention as illustrated in the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a cross-sectional view schematically showing a
multilayered structure of a conventional lapping control
sensor;
[0020] FIG. 2 is a view schematically showing a plane structure of
a lapping control sensor of a preferred embodiment of the present
invention;
[0021] FIG. 3 is a cross-sectional view schematically showing the
multi-layered structure of a lapping control sensor of FIG. 2;
[0022] FIGS. 4a to 4d are cross-sectional views explaining the
manufacturing method of the lapping control sensor;
[0023] FIG. 5 is a characteristic diagram illustrating the
relationship between a thickness of an insulation layer of the
lapping control sensor and an error ratio of resistance
measurement;
[0024] FIGS. 6a to 6c are characteristic diagrams of the change in
measured values of resistance with respect to lapping time when the
thickness of the insulation layer is small; and
[0025] FIGS. 7a to 7c are characteristic diagrams of the change in
measured values of resistance with respect to lapping time when the
thickness of the insulation layer is large.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] FIG. 2 illustrates a plan view of MR heads and a lapping
control sensor in a part of a bar obtained by cutting each of rows
of a wafer in which numerous MR heads were arranged in a matrix.
FIG. 2 is, however, a transparent view because an inductive head
and the like have actually been mounted on the bar and thus these
MR heads and the lapping control sensor cannot be directly seen
from outside.
[0027] In the figure, reference numerals 20 and 20a denote the bar
and the ABS surface to be lapped of the bar 20. Also, reference
numerals 21 and 22 denote two of a plurality of MR heads formed in
one row along the bar 20, 23 denotes one of lapping control sensors
formed in a space between the MR heads in parallel therewith. In
this case, it is desirable that another lapping control sensors are
provided at both end portions of the bar 20.
[0028] In FIG. 2, furthermore, reference numerals 21a and 22a
denote MR layers of the respective MR heads 21 and 22 formed on a
shield gap insulation layer, 21b and 21c, and 22b and 22c denote
lead conductors connected across the respective MR layers 21a and
22a. Also, reference numeral 23a denotes a resister layer of the
lapping control sensor 23, and 23b and 23c denote lead conductors
connected across the resistor layer 23a As shown in the figure, the
MR layers 21a and 22a and the resister layer 23a are disposed in
parallel with the ABS surface 20a so that one sides of the layers
are adjacent to the ABS surface 20a.
[0029] FIG. 3 illustrates the multi-layered structure of the
lapping control sensor 23 shown in FIG. 2. In FIG. 3, reference
numeral 30 denotes a metallic layer made of the same material and
provided with the same layer thickness as those of the lower shield
layer of the MR head, and 31 denotes an insulation layer made of
the same material as that of the shield gap insulation layer of the
MR head but provided with a layer thickness of for example 0.1
.mu.m which is larger than that of the lower shield layer of the MR
head. Also reference numeral 32 (23a) denotes a resister layer made
of the same material and provided with the same layer thickness as
those of the MR layer of the MR head, and 33 and 34 (23b and 23c)
denote lead conductors made of the same material and provided with
the same layer thickness as those of the lead conductor of the MR
head.
[0030] FIGS. 4a to 4d are cross-sectional views explaining a
manufacturing method of the lapping control sensor of the
embodiment shown in FIG. 2. The metallic layer 30 is first formed
on an under layer (not shown). This metallic layer 30 is formed by
the same processes as the formation of the lower shield layer of
the MR head. Therefore, the layer 30 is formed made of the same
material and provided with the same thickness as those of the lower
shield layer.
[0031] Then, as shown in FIG. 4b, an insulation layer 31' is formed
on the layer 30 and on the under layer. This insulation layer 31'
is formed by the same processes as the formation of the shield gap
insulation layer of the MR head. Therefore, the layer 31' is made
of the same material and provided with the same thickness as those
of the shield gap insulation layer. Then, as shown in FIG. 4c, on
the insulation layer 31' of only the lapping control sensor, an
insulation material is further deposited by using a lift off
process or the like so as to form an insulation layer 31 having a
thickness of for example 0.1 .mu.m or more, which is greater than
that of the insulation layer in other areas. The insulation layer
31 having such a greater thickness may be formed on only the
lapping control sensor as mentioned above, or on any area other
than the MR head area.
[0032] Then, as shown in FIG. 4d, the resister layer 32 (23a) is
formed on the insulation layer 31. This resister layer 32 (23a) is
also formed by the same processes as the formation of the MR layer
of the MR head. Therefore, the resister layer 32 (23a) is made of
the same material and provided with the same thickness as those of
the MR layer. Then, as shown in FIG. 3, the lead conductors 33
(23b) and 34 (23c) connected across the resister layer 32 (23a) are
formed. These lead conductors 33 (23b) and 34 (23c) are also formed
by the same processes as the formation of lead conductors of the MR
head. Therefore, the lead conductors 33 (23b) and 34 (23c) are made
of the same material and provided with the same thickness as those
of the lead conductors of the MR head.
[0033] In this embodiment of the present invention, the insulation
layer of the lapping control sensor is formed to have a thickness
of 0.1 .mu.m or more which is greater than the thickness of the
shield gap insulation layer of the MR head. Therefore, when the bar
20 is lapped from the ABS surface 20a side to control the MR height
using this sensor, the formation of short circuits between the lead
conductors 33 (23b) and 34 (23c) due to smears produced can be
prevented. Therefore, the generation of noises in detecting outputs
can be also securely prevented.
[0034] FIG. 5 illustrates relationships between a thickness of the
insulation layer of the lapping control sensor and an error ratio
of the resistance measurement. Marks and .times. represent
characteristics of lapping control sensors with the metallic layers
30 made of different materials, respectively. the error ratio of
the resistance measurement is given from the number of continuous
abnormal measurements divided by the total number of measurements.
The measurement period of resistance is 0.1 sec. The number of
continuous abnormal measurements means the number of measurements
in which measured values of resistance did not continuously
indicate normal resistance values during lapping process of the
same bar. The normal resistance value means that the measured value
of resistance is larger than the last measured value (the value
measured at 0.1 sec. before) and that the measured value of
resistance is larger than the maximum measured value of resistance
measured during the lapping process of the same bar.
[0035] It has been found from experience that when the error ratio
of resistance measurement is larger than 1.5%, a lapping control
using a lapping control sensor becomes impossible. Thus, it is
necessary from FIG. 5 that the thickness of the insulation layer of
a lapping control sensor is 0.1 .mu.m or more.
[0036] FIGS. 6a to 6c indicate change in measured values of
resistance with respect to lapping time for various samples of the
lapping control sensor with a thin insulation layer having a
thickness of 0.08 .mu.m. Whereas FIGS. 7a to 7c indicate change in
measured values of resistance with respect to lapping time for
various samples of the lapping control sensor with a thick
insulation layer having a thickness of 0.1 .mu.m or more.
[0037] As apparent from FIGS. 6a to 6c and FIGS. 7a to 7c, when the
insulation layer is thin as 0.08 .mu.m, a large amount of noise is
found in measured values of resistance. However, when the
insulation layer is thick as 0.1 .mu.m, no noise is found and
measured values of resistance are increased in accordance with
passage of time. Therefore, by executing the lapping control using
the latter lapping control sensor, it can be securely and stably
control an MR height of the MR head to a corrective value.
[0038] Since the MR head has a thin shield gap insulation layer,
smears may be produced during controlling the MR height, resulting
that the smears may produce short circuits between lead conductors
of the MR head. However, since the method of manufacturing the MR
head includes the steps of controlling the MR height without using
lead conductors and removing such smears, no problems occur.
[0039] Many widely different embodiments of the present invention
may be constructed without departing from the spirit and scope of
the present invention. It should be understood that the present
invention is not limited to the specific embodiments described in
the specification, except as defined in the appended claims.
* * * * *