Magnetoresistance effect magnetic head and manufacturing method therefor

A magnetoresistance effect magnetic head which is capable of shortening shield gap distance and which can be manufactured by a small number of manufacturing steps, and a manufacturing method therefor are provided. The magnetoresistance effect magnetic head having a magnetoresistance effect magnetic device held between a pair of soft magnetic members through insulating layers and conductors connected to the magnetoresistance effect magnetic device is structured such that the conductors are embedded in grooves formed in the insulating layer. Since the magnetoresistance effect magnetic device has the structure such that the conductors connected to the magnetoresistance effect magnetic device are embedded in the grooves formed in the insulating layer, the shield gap distance can be shortened.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a magnetoresistance effect magnetic head 
for a high density digital recording and reproducing apparatus, such as a 
digital tape recorder or a data storage, and to a manufacturing method 
therefor. 
2. Description of Prior Art 
In recent years, the recording density realized by magnetic recording has 
been raised, thus resulting in that a demand for a thin film magnetic head 
being heightened which is able to advantageously reduce the width of the 
track, lower the inductance and raise the transfer rate to be adaptable to 
the raised recording density as compared with the conventional bulk type 
magnetic head which has been used widely. 
Since the thin film magnetic head is, similarly to a semiconductor 
integrated circuit, manufactured by using a film forming technology, such 
as evaporation and sputtering, and a photolithography technology, such as 
a photomechanical process and etching, a multiplicity of thin film 
magnetic heads can collectively and accurately be manufactured on one 
wafer. Thus, the thin film magnetic head can satisfactorily be 
mass-produced. Therefore, the thin film magnetic head is expected to be 
mainly used as a magnetic head employed in a magnetic recording apparatus, 
such as a hard disk drive. 
In the above-mentioned circumstance, also the thin film magnetic head is 
required to have improved performance to be adaptable to the further 
raised recording density. To improve the performance, a magnetic head has 
been researched and developed which has a structure formed by combining an 
inductive thin film magnetic head and a magnetoresistance effect magnetic 
head (hereinafter called as a "MR head") to record an information signal 
by using the inductive thin film magnetic head and to reproduce an 
information signal by using the MR head. Moreover, a combined type thin 
film magnetic head, having a structure arranged such that the inductive 
thin film magnetic head and the MR head are formed on one substrate 
thereof, has been put into practical use. 
The MR head is a magnetic head using the magnetic resistance effect of a 
magnetoresistance effect magnetic device (hereinafter called as an "MR 
device") to reproduce a recorded signal. The MR head is different from a 
usual magnetic induction type magnetic head, that is, a magnetic head 
having a structure in which a wire is wound around a magnetic core, in 
that the output reproduced from the MR head does not depend upon the 
relative speed from a recording medium. Namely, the MR head is able to 
obtain a satisfactorily large output even from a relatively low speed 
system. Therefore, the MR head is considered to be an essential device for 
realizing higher density recording and reproducing. 
The MR head is mainly classified into a non-shield MR head structured such 
that the two side surfaces of the MR device are held by non-magnetic 
members; a shield MR head structured such that the two side surfaces of 
the MR device are shielded by soft magnetic members for the purpose of 
improving the reproduction frequency characteristic of the non-shield MR 
head; and a yoke type MR head structured such that magnetic flux from a 
recording medium is introduced into the MR device and the MR device is 
formed into a non-exposed type structure in order to stabilize various 
characteristics, such as wear resistance. Among the above-mentioned MR 
heads, the shield MR head has been made most practical. The reason for 
this is that the shield MR head has a frequency characteristic superior to 
that of the non-shield MR head and thus excellent resolution can be 
obtained. Moreover, the shield MR head can easily be manufactured as 
compared with the yoke type MR head and large reproduction output can be 
obtained. 
The shield MR head is classified into a lateral type head in which a sense 
current flows in the widthwise direction of the track and a vertical type 
head in which the sense current flows perpendicular to the widthwise 
direction of the track. At present, the lateral type shield MR head is 
mainly used. 
The conventional lateral type shield MR head has a structure arranged as 
shown in FIGS. 1 to 4. FIG. 1 is a plan view showing a circuit pattern of 
the lateral type shield MR head, and FIG. 2 is a cross sectional view 
taken along line I-I' shown in FIG. 1. FIG. 3 is a cross sectional view 
taken along line J-J' shown in FIG. 1. FIG. 4 is a schematic perspective 
view showing the conventional lateral type shield MR head. 
As shown in FIGS. 1 to 4, the lateral type shield MR head is composed of a 
MR device portion 105 consisting of a first soft magnetic substrate 101, 
an insulating layer 102 formed on the first soft magnetic substrate 101, a 
MR device 103 and a biasing conductor 104 formed on the insulating layer 
102; a pair of conductors 106 and 107 extending from the two lengthwise 
directional ends of the MR device portion 105; an insulating layer 108 
formed on the MR device portion 105 and the conductors 106 and 107; and a 
second soft magnetic substrate 110 connected to the upper surface of the 
insulating layer 108 by an adhesive agent 109. 
The biasing conductor 104 is provided for the purpose of applying a bias 
magnetic field to the MR device 103, the biasing conductor 104 being 
formed on the MR device 103. The MR device portion 105 formed by 
laminating the MR device 103 and the biasing conductor 104 is disposed in 
such a manner that its longitudinal direction runs parallel to a surface M 
facing a recording medium. Moreover, one of the ends of the MR device 
portion 105 is ground so as to be exposed to the surface M facing the 
recording medium. 
When an information signal is reproduced from the recording medium by using 
the above-mentioned MR head, a sense electric current is supplied to the 
MR device portion 105 through the conductors 106 and 107. As a result, the 
sense electric current flows in the lengthwise direction of the MR device 
portion 105 along the surface M facing the recording medium. 
In the above-mentioned MR head, it is preferable that each of the 
conductors 106 and 107 has small electric resistance because the sense 
electric current is supplied to the MR device portion 105 through the 
conductors 106 and 107. Since the portions of the conductors 106 and 107 
which are connected to the MR device portion 105 are exposed to the 
surface M facing the recording medium and thus the portions come in 
contact with the outside air, the portion must have environment 
resistance. 
Accordingly, the conductors 106 and 107 are divided into portions which are 
exposed to the surface M facing the recording medium and thus brought into 
contact with the outside air and portions which do not exposed to the 
surface M facing the recording medium and thus they are not brought into 
contact with the outside air, the divided portions being made of different 
materials. 
That is, the conductors 106 and 107 are composed of first conductors 106a 
and 107a extending from two lengthwise directional ends of the MR device 
portion 105 and second conductors 106b and 107b extending from the rear 
ends of the first conductors 106a and 107a. 
Since the first conductors 106a and 107a are exposed to the surface M 
facing the recording medium and thus they are brought into contact with 
the outside air, the first conductors 106a and 107a must have satisfactory 
environment resistance rather than the electric characteristics. Thus, the 
first conductors 106a and 107a are made of metal having a high melting 
point to have satisfactory environment resistance. On the other hand, 
since the second conductors 106b and 107b are not exposed to the surface M 
facing the recording medium and thus they are not brought into contact 
with the outside air, the second conductors 106b and 107b must have 
satisfactory electric characteristics rather than the environment 
resistance. Therefore, the second conductors 106b and 107b are made of a 
conductive material having a small specific resistance. 
When the lateral type shield MR head is manufactured, the first step is 
performed such that the insulating layer 102 is, by sputtering or the 
like, formed on the first soft magnetic substrate 101. Then, the MR device 
103 and the biasing conductor 104, for applying the bias magnetic field to 
the MR device 103, are formed on the insulating layer 102. Then, the 
foregoing elements are formed to have predetermined shapes by 
photolithography so that the MR device portion 105 is formed. 
Then, the first conductors 106a and 107a are formed to extend from the two 
ends of the MR device portion 105 to cover the upper surface of the 
insulating layer 102, that is, to extend from the two lengthwise 
directional ends of the MR device portion 105. Then, the second conductors 
106b and 107b are laminated on the rear portions of the first conductors 
106a and 107a. 
As described above, the first conductors 106a and 107a and the second 
conductors 106b and 107b for supplying the sense electric current to the 
MR device portion 105 are made such that the first conductors 106a and 
107a are made of the material having excellent environment resistance and 
the second conductors 106b and 107b are made of the material having small 
specific resistance. 
Then, the insulating layer 108 is formed on the overall surface, and then 
the second soft magnetic substrate 110 are connected to the insulating 
layer 108 by the adhesive agent 109. The second soft magnetic substrate 
110 is connected in such a manner that portions of the rear ends of the 
second conductors 106b and 107b are exposed to serve as electrodes for 
establishing the connection with the outside. 
After the above-mentioned processes have been completed, a grinding process 
for grinding the surface M facing the recording medium to expose the MR 
device portion 105 to the surface M facing the recording medium is 
performed, and then a terminal forming process is performed such that 
terminals for establishing the connection with the outside are formed in 
the electrode portions at the rear ends of the second conductors 106b and 
107b. As a result, the above-mentioned lateral type shield MR head can be 
manufactured. 
The frequency characteristics of the lateral type shield MR head having the 
above-mentioned structure are determined by shield gap distance g between 
the first soft magnetic substrate 101 and the second soft magnetic 
substrate 110. The frequency characteristics are improved in inverse 
proportion to the shield gap distance g. Thus, an information signal 
having a higher density can be reproduced. 
Since the shield MR head has the structure such that the MR device 103, the 
biasing conductor 104 and the conductors 106 and 107 are held between the 
first soft magnetic substrate 101 and the second soft magnetic substrate 
110, the shield gap distance g is mainly determined by the thicknesses of 
the MR device 103, the biasing conductor 104 and the conductors 106 and 
107. Since the conductors 106 and 107 have the largest thickness in 
general, the shield gap distance g is determined by the thickness of the 
conductors 106 and 107. 
Therefore, it is preferable for the shield MR head that the thickness of 
the conductors 106 and 107 be reduced to shorten the shield gap distance 
g. However, since reduction in the thickness of the conductors 106 and 107 
results in the electric resistance of each of the conductors 106 and 107 
being enlarged, the load of a sense electric current circuit for 
controlling the sense electric current which is supplied to the MR device 
portion 105 is made to be heavier and the impedance is as well as 
enlarged. As a result, noise level is raised unsatisfactorily. Therefore, 
the shield MR head having the above-mentioned structure encounters a 
difficulty in reducing the thickness of the conductors 106 and 107. Thus, 
the shield gap distance g cannot be made to be a satisfactory value. 
To solve the above-mentioned problem, a shield MR head having a structure 
arranged as shown in FIGS. 5 and 6 has been suggested. FIG. 5 is a plan 
view showing a pattern of a circuit in the shield MR head, and FIG. 6 is a 
cross sectional view taken along line K-K' shown in FIG. 5. 
The foregoing shield MR head has a structure such that a portion of the 
insulating layer 108, formed on the overall surface after the first 
conductors 106a and 107a and the second conductors 106b and 107b have been 
formed, is etched, the portion being a portion formed on the first 
conductors 106a and 107a. Thus, the thickness of the insulating layer 108 
is reduced in order to prevent projection of the insulating layer 108 over 
the first conductors 106a and 107a. As a result, the influences of the 
first conductors 106a and 107a and the second conductors 106b and 107b on 
the shield gap distance g can be limited. Thus, the shield gap distance g 
can be reduced. As described above, the shield MR head of the foregoing 
type is able to reduce the shield gap distance g so that a relatively 
satisfactory frequency characteristic is obtained. 
However, the shield MR head shown in FIGS. 5 and 6 must have a process for 
etching the portions of the insulating layer 108 on the first conductors 
106a and 107a, the insulating layer 108 being formed on the overall 
surface after the second conductors 106b and 107b have been formed. Thus, 
there arises a problem in that the number of manufacturing steps cannot be 
reduced. That is, the above-mentioned shield MR head must have the etching 
process using the photolithography after the insulating layer 108 has been 
formed. As a result, the number of manufacturing step is unintentionally 
increased. 
SUMMARY OF THE INVENTION 
In view of the foregoing, an object of the present invention is to provide 
a MR head which is capable of shortening the shield gap distance and which 
can be manufactured by a small number of manufacturing processes. 
In order to achieve the above-mentioned object, according to one aspect of 
the present invention, there is provided a MR head having a 
magnetoresistance effect magnetic device held between a pair of soft 
magnetic members through insulating layers and conductors connected to the 
magnetoresistance effect magnetic device and structured such that the 
conductors are embedded in grooves formed in the insulating layer. 
The MR head according to the present invention has a structure such that 
one of the soft magnetic members is bonded to the insulating layer with, 
for example, adhesive agent. 
It is preferable that the MR head has a structure such that a second 
conductor having specific resistance weaker than that of the conductor is 
connected to the conductor. 
It is preferable that the MR head has a structure such that magnetic layers 
are formed at the two ends of the magnetoresistance effect magnetic 
device. The magnetic layer in the foregoing structure may have, for 
example, conductivity and structured to restrict the width of the track by 
the distance between one of the magnetic layers and the other magnetic 
layer. 
Since the MR head according to the present invention has the structure such 
that the conductors connected to the magnetoresistance effect magnetic 
device are embedded in the grooves formed in the insulating layer, the 
shield gap distance can be shortened. 
According to another aspect of the present invention, there is provided a 
method of manufacturing a MR head having a magnetoresistance effect 
magnetic device held between a pair of soft magnetic members through 
insulating layers and conductors connected to the magnetoresistance effect 
magnetic device, the method of manufacturing a MR head comprising the 
steps of etching the insulating layer to form grooves when the conductors 
are formed, and forming the conductors in the grooves. 
The method of manufacturing the MR head is structured such that one of the 
soft magnetic members is bonded to the insulating layer with, for example, 
adhesive agent. 
It is preferable that the method of manufacturing a MR head be structured 
such that a second conductor having specific resistance weaker than that 
of the conductor is formed after the conductor has been formed in such a 
manner that the second conductor is connected to the conductor. 
It is preferable that the method of manufacturing a MR head is structured 
such that magnetic layers are formed at the two ends of the 
magnetoresistance effect magnetic device after the magnetoresistance 
effect magnetic device has been formed. A structure may be employed in 
which the distance between the two magnetic layers is used to restrict the 
width of the track. 
Since the method of manufacturing a MR head according to the present 
invention has a structure such that the grooves are formed in the 
insulating layer and the conductors connected to the magnetoresistance 
effect magnetic device are formed so as to be embedded in the grooves, the 
shield gap distance can be shortened. 
Other objects, features and advantages of the invention will be evident 
from the following detailed description of the preferred embodiments 
described in conjunction with the attached drawings.

DETAILED DESCRIPTION OF THE INVENTION 
Embodiments of a MR head according to the present invention will now be 
described with reference to the drawings. Note that the present invention 
is not limited to the following description and arbitrary change in the 
shape, materials and so forth without departing from the scope of the 
present invention. 
First Embodiment 
The structure of a MR head according to a first embodiment is shown in 
FIGS. 7 to 10. FIG. 7 is a plan view showing a pattern of a circuit in the 
MR head according to this embodiment. FIG. 8 is a cross sectional view 
taken along line A-A' shown in FIG. 7. FIG. 9 is a cross sectional view 
taken along line B-B' shown in FIG. 7. FIG. 10 is a cross sectional view 
taken along line C-C' shown in FIG. 7. 
As shown in FIGS. 7 to 10, the MR head according to this embodiment has a 
MR device portion 5 consisting of a first soft magnetic substrate 1, an 
insulating layer 2 formed on the first soft magnetic substrate 1, a MR 
device 3 and a biasing conductor 4 formed on the insulating layer 2; a 
pair of conductors 6 and 7 extending from the two lengthwise directional 
ends of the MR device portion 5; a pair of second conductors 8 and 9 
respectively connected to the pair of the first conductors 6 and 7; 
insulating layers 10a and 10b formed to cover the MR device portion 5, the 
first conductors 6 and 7 and the second conductors 8 and 9; and a second 
soft magnetic substrate 12 bonded to the upper surface of the insulating 
layer 10b by an adhesive agent 11. 
The MR head according to this embodiment has a structure such that the MR 
device portion 5 is composed of the MR device 3 and the biasing conductor 
4 formed on the MR device 3 to apply a bias magnetic field. The MR device 
portion 5 is disposed in such a manner that such that its lengthwise 
direction runs parallel to a surface M facing a recording medium. The MR 
device portion 5 is ground in such a manner that one of its ends are 
exposed to the surface M facing the recording medium. 
The first conductors 6 and 7 extending from the two ends of the MR device 
portion 5 are, in a region from the end of the MR device portion 5 to 
reach the upper surface of the insulating layer 2, embedded in a groove 
formed in the insulating layer 10a in such a manner that the front ends of 
the first conductors 6 and 7 are exposed to the surface M facing the 
recording medium. On the other hand, the second conductors 8 and 9 
connected to the first conductors 6 and 7 are laminated on the rear ends 
of the first conductors 6 and 7 in such a manner that the second 
conductors 8 and 9 are not exposed to the surface M facing the recording 
medium. The insulating layer 10b is formed on the first conductors 6 and 7 
and the second conductors 8 and 9. 
That is, as shown in FIG. 9, the MR head according to this embodiment has a 
structure such that the second conductor 8 is laminated on the rear end of 
the first conductor 6 embedded in the groove formed in the insulating 
layer 10a so that the first conductor 6 and the second conductor 8 are 
electrically connected to each other. Moreover, the insulating layer 10b 
is formed on the first conductor 6 and the second conductor 8. The 
insulating layer 10b is formed in such a manner that a connecting terminal 
13 formed at the rear end of the second conductor 8 is exposed to the 
outside. 
Similarly, the second conductor 9 is laminated on the rear end of the first 
conductor 7 embedded in the groove formed in the insulating layer 10a so 
that the first conductor 7 and the second conductor 9 are electrically 
connected to each other. Moreover, the insulating layer 10b is formed on 
the first conductor 7 and the second conductor 9. The insulating layer 10b 
is formed in such a manner that a connecting terminal 14 formed at the 
rear end of the second conductor 9 is exposed to the outside. 
The first conductors 6 and 7 are made of metal having a high melting point 
and exhibiting excellent environment resistance. The reason for this is 
that the structure in which the first conductors 6 and 7 are exposed to 
the surface M facing the recording medium requires the excellent 
environment resistance. On the other hand, the second conductors 8 and 9 
are made of conductive material having a specific resistance weaker than 
that of the first conductors 6 and 7. The reason for this is that the 
electric characteristics can be given priority to the environment 
resistance because the second conductors 8 and 9 are not exposed to the 
surface M facing the recording medium. 
When an information is reproduced from the recording medium by using the MR 
head having the above-mentioned structure, sense electric currents are 
supplied from the connecting terminals 13 and 14 formed at the rear ends 
of the second conductors 8 and 9 to the MR device portion 5 through the 
second conductors 8 and 9 and the first conductors 6 and 7 so as to allow 
the sense electric currents to flow in the lengthwise direction of the MR 
device portion 5 along the surface M facing the recording medium. The 
sense electric currents are used to detect change in the resistance of the 
MR device portion 5 occurring attributable to the magnetic field formed 
from the recording medium so that the information signal is reproduced 
from the recording medium. 
Note that the first soft magnetic substrate 1 and the second soft magnetic 
substrate 12 of the MR head according to this embodiment are formed in 
order to magnetically shield the MR device portion 5. Therefore, the 
overall body of each of the first soft magnetic substrate 1 and the second 
soft magnetic substrate 12 is not required to be made of the soft magnetic 
material. As a result, a structure may be employed in which a thin soft 
magnetic film is formed on a non-magnetic substrate or a magnetic 
substrate so as to serve as the first soft magnetic substrate 1 and the 
second soft magnetic substrate 12. Moreover, the thin soft magnetic film 
is allowed to face the MR device portion 5. 
A method of manufacturing the MR head having the above-mentioned structure 
will now be described with reference to FIGS. 11 to 22. FIGS. 11 to 16 and 
FIG. 22 show the state of the cross sectional portion taken along line 
A-A' shown in FIG. 7 in the sequential order of the manufacturing 
processes. FIGS. 17 to 21 show the state of the cross sectional portion 
taken along line B-B' shown in FIG. 7 in the sequential order of the 
manufacturing processes. 
When the above-mentioned MR head is manufactured, a first process is 
performed as shown in FIG. 11 such that the insulating layer 2 made of 
Al.sub.2 O.sub.3 or SiO.sub.2 (silicon oxide) is, by sputtering or the 
like, formed on the first soft magnetic substrate 1 made of polycrystal 
ferrite, such as Ni-Zn hematite, which is the soft magnetic material, in 
such a manner that the thickness of the insulating layer 2 is about 0.2 
.mu.m to about 0.3 .mu.m. Since the surface of the insulating layer 2 is 
formed into the surface on which the MR device 3 will be formed in the 
post process, it is preferable that the surface roughness of the 
insulating layer 2 be improved. Therefore, after the insulating layer 2 
has been formed, the surface of the insulating layer 2 is mirror-finished 
or subjected to surface treatment by using coating type SiO.sub.2 called 
"Spin On Glass (SOG)". 
Then, the MR device portion 5 is formed on the insulating layer 2, as shown 
in FIG. 12. The MR device portion 5 is, as described above, formed by 
laminating the MR device 3 and the biasing conductor 4 for applying a bias 
magnetic field to the MR device 3 in order to apply a DC bias magnetic 
field to the MR head by a so-called SAL bias method. When the MR device 
portion 5 is formed, the MR device 3 and the biasing conductor 4 are 
laminated by sputtering or evaporation. Then, the MR device 3 and the 
biasing conductor 4 are simultaneously etched into an elongated shape in 
such a manner that their lengthwise direction runs parallel to the surface 
M facing the recording medium. As a result, the MR device portion 5, the 
lengthwise direction of which runs parallel to the surface M facing the 
recording medium, is formed on the insulating layer 2. 
The MR device 3 is made of, for example, a Ni--Fe alloy, while the biasing 
conductor 4 is made of a laminate of Ta and a Ni--Fe--Ta alloy. In this 
embodiment, the MR device 3 is made of a Ni--Fe alloy having a thickness 
of about 50 nm, while the biasing conductor 4 is made of a laminate of Ta 
having a thickness of about 10 nm and a Ni--Fe--Ta alloy having a 
thickness of about 50 nm. Therefore, the overall thickness of the MR 
device portion 5 of the MR head according to this embodiment is about 110 
nm. 
Note that the laminating order of the MR device 3 and the biasing conductor 
4 may be reversed That is, the Ni--Fe--Ta alloy, Ta and the Ni--Fe alloy 
may be laminated in this sequentially order. 
Then, as shown in FIG. 13, the insulating layer 10a made of Al.sub.2 
O.sub.3, SiO.sub.2 or the like is formed on the insulating layer 2 and the 
MR device portion 5 by sputtering or the like to have a thickness of about 
0.1 .mu.m. Note that the insulating layer 10a may be made of insulating 
material, such as NiO, having antiferromagnetism. When the insulating 
layer 10a is made of the insulating material having the 
antiferromagnetism, the magnetic stability of the MR device 3 can be 
improved thanks to the antiferromagnetic binding between the insulating 
layer 10a and the MR device 3. 
Then, two grooves are formed in the insulating layer 10a in a direction 
substantially perpendicular to the medium sliding surface in order to 
expose the two portions of the MR device portion 5. The grooves are formed 
as shown in FIG. 14 such that a resist 20 having an inversely tapered 
openings corresponding to the grooves is formed on the insulating layer 
10a and then the resist 20 is used as a mask when the insulating layer 10a 
is etched by ion milling or the like. The grooves are formed for the 
purpose of embedding the first conductors 6 and 7 in the following 
process, the first conductors 6 and 7 being arranged to supply the sense 
electric currents to the MR device portion 5. 
Then, as shown in FIG. 15, the conductive films 21, which are formed into 
the first conductors 6 and 7, are formed on the overall surface by 
sputtering or the like. As a result, the conductive films 21 are formed in 
the grooves formed in the insulating layer 10a and also formed on the 
resist 20. The thickness of the conductive film 21 is made to be the same 
as that of the insulating layer 10a or smaller than the same. Since the 
first conductors 6 and 7 must have excellent environment resistance as 
described above, the conductive film 21 is made of Cr, Ti, Ta, W, Mo or 
the like which is metal having excellent environment resistance and a high 
melting point or their alloys. 
Then, the resist 20 is separated by using organic solvent or the like. As a 
result, the conductive film 21 formed on the resist 20 is removed together 
with the resist 20. Thus, the conductive films 21 are retained only in the 
grooves, that is, only the portions embedded in the insulating layer 10a 
are retained. The retained portions are formed into the first conductors 6 
and 7. Since the first conductors 6 and 7 have the thickness which is 
smaller than that of the insulating layer 10a, they do not affect the 
shield gap distance g1. 
The above-mentioned method in which unnecessary portions are masked with 
the resists and the masks are then separated to form a required pattern is 
called a "lift off method". 
Since the sense electric current, which is supplied to the MR device 
portion 5, flows between the two first conductors 6 and 7, an effective 
portion, from which the magnetic field from the recording medium is 
detected, is only the portion between the two first conductors 6 and 7. As 
a result, distance T1 from the first conductor 6 to the first conductor 7 
is the width of the track of the MR head. Therefore, the pair of the first 
conductors 6 and 7 are formed in such a manner that the distance from the 
first conductor 6 to the first conductor 7 is made to be a required width 
of the track. 
After the first conductors 6 and 7 have been formed as described above, the 
second conductors 8 and 9 are formed by the lift off method similarly to 
the first conductors 6 and 7. The process for manufacturing the second 
conductors will be described with reference to FIGS. 17 to 20 which are 
cross sectional views taken along line B-B' shown in FIG. 7. FIG. 17 
corresponds to FIG. 16 and shows the state after the first conductors 6 
and 7 have been formed. 
When the second conductors 8 and 9 are formed, the first conductors 6 and 7 
are formed as shown in FIGS. 16 and 17 and then the resist 22 is formed as 
shown in FIG. 18. The resist 22 is formed in such a manner that openings 
are formed to correspond to the rear ends of the first conductors 6 and 7 
and the resist 22 fully covers the other portions. The openings of the 
resist 22 are formed in such a manner that the edge portions of the 
openings are inversely tapered. 
Then, as shown in FIG. 19, a conductive film 23 for forming the second 
conductors 8 and 9 is formed on the overall surface by sputtering or the 
like. Since the edge portion of the resist 22 is inversely tapered, the 
conductive film 23 formed in the opening of the resist 22 and the 
conductive film 23 formed on the resist 22 are not connected to each 
other, that is, they are completely separated from each other, as shown in 
FIG. 19. It is preferable that the second conductors 8 and 9 be made of 
the conductive material having small specific resistance as described 
above. Therefore, the conductive film 23 for forming the second conductors 
8 and 9 is made of Cu, Ag or Au type material or a laminate formed by 
laminating the foregoing conductive material on a base film made of Ti or 
the like. 
As described above, the conductive film 23 is formed in such a manner that 
its thickness is smaller than that of the MR device portion 5. Since the 
MR head according to this embodiment has the structure such that the 
thickness of the MR device portion 5 is about 110 nm, the thickness of the 
conductive film 23 is made to be smaller than 110 nm. 
The shapes of the second conductors 8 and 9 are required to be connected to 
the first conductors 6 and 7. That is, the patterns of the second 
conductors 8 and 9 may be formed into shapes which coincide with the rear 
ends of the first conductors 6 and 7. As an alternative to this, the 
patterns may be formed into wide shapes capable of covering the rear ends 
of the first conductors 6 and 7. The patterns may be narrower than those 
of the rear ends of the first conductors 6 and 7. In this embodiment, the 
second conductors 8 and 9 are formed into shapes, the width of each of 
which is smaller than the width of each of the first conductors 6 and 7, 
as shown in FIG. 7. 
Then, as shown in FIG. 20, the second conductors 8 and 9 are formed into 
predetermined shapes by the lift off method. That is, organic solvent is 
used to remove the resist 22 together with the conductive film 23 formed 
on the resist 22. Since the second conductors 8 and 9 formed in the 
openings of the resist 22 and the second conductors 8 and 9 formed on the 
resist 22 are completely separated from each other, the edge portions of 
the second conductors 8 and 9 formed in the openings of the resist 22 are 
not disordered and only the conductive film 23 formed on the resist 22 can 
reliably be removed. 
As a result of the above-mentioned process, the second conductors 8 and 9 
are formed on the first conductors 6 and 7. 
Each of the second conductors 8 and 9 has a thickness smaller than that of 
the MR device portion 5. Therefore, the thickness of a portion in which 
the first conductor 6 and the second conductor 8 are laminated and the 
thickness of the portion in which the first conductor 7 and the second 
conductor 9 are laminated are smaller than the thickness of a portion in 
which the MR device portion 5 and the first conductor 6 are laminated and 
the thickness of a portion in which the MR device portion 5 and the first 
conductor 7 are laminated. As a result, the portions, in which the second 
conductors 8 and 9 are formed, are made to be lower than the portions on 
the MR device portion 5 in which the first conductors 6 and 7 are formed. 
Therefore, the second conductors 8 and 9 do not affect the shield gap 
distance g1. 
Then, the insulating layer 10b made of Al.sub.2 O.sub.3 or SiO.sub.2 is, as 
shown in FIGS. 21 and 22, formed on the MR device portion 5, the 
insulating layer 10a, the first conductors 6 and 7 and the second 
conductors 8 and 9 by sputtering or the like to have a thickness of about 
0.1 .mu.m. The insulating layer 10b is formed for the purpose of 
protecting the first conductors 6 and 7 and the second conductors 8 and 9 
from static electricity and corrosion. 
The highest portion with respect to the main surface of the first soft 
magnetic substrate 1 is the portion in which the insulating layer 10a and 
the insulating layer 10b are formed on the MR device portion 5. Therefore, 
the shield gap distance g1 is determined by the MR device portion 5, 
composed of the insulating layer 2 formed on the first soft magnetic 
substrate 1, the MR device 3 and the biasing conductor 4, and the 
insulating layer 10a and the insulating layer 10b formed on the MR device 
portion 5. That is, the MR head according to this embodiment has the 
structure such that the first conductors 6 and 7 and the second conductors 
8 and 9 do not affect the shield gap distance g1. 
Then, the portions of the rear ends of the second conductors 8 and 9 are 
exposed to serve as the electrodes for establishing the connection with 
the outside by completely removing the insulating layer 10b formed on the 
rear ends of the second conductors 8 and 9 by etching and by bonding the 
second soft magnetic substrate 12 to the upper surface of the insulating 
layer 10b by using an adhesive agent. In this process, the second soft 
magnetic substrate 12 is joined up in such a manner that the rear ends of 
the second conductors 8 and 9 are exposed. 
After the above-mentioned process has been completed, a post process is 
performed which includes a grinding process for grinding the surface M 
facing the recording medium for exposing the MR device 3 to the surface M 
facing the recording medium and a terminal forming process for forming the 
connecting terminals 13 and 14 for establishing the connection with the 
outside in the electrode portions at the rear ends of the second 
conductors 8 and 9. As a result, the MR head according to this embodiment 
is manufactured. Since the MR head according to this embodiment has the 
structure such that the first conductors 6 and 7 and the second conductors 
8 and 9 do not affect the shield gap distance g1 as described above, the 
width of the shield gap distance g1 can be reduced. 
Second Embodiment 
In general, the MR head suffers from a problem in that Barkhausen noise is 
generated attributable to movement of the magnetic domain wall in the MR 
device. As a method of eliminating the Barkhausen noise, a method has been 
known in which the MR device is formed into a single magnetic domain by 
applying a magnetic field to the MR device. Therefore, a MR head according 
to this embodiment has a structure arranged such that magnetic layers are 
formed at the two ends of the MR device and the magnetic layers apply 
magnetic fields to the MR device. 
The structure of the MR head according to this embodiment is shown in FIGS. 
23 to 26. FIG. 23 is a plan view showing a pattern of a circuit in the MR 
head according to this embodiment. FIG. 24 is a cross sectional view taken 
along line D-D' shown in FIG. 23. FIG. 25 is a cross sectional view taken 
along line E-E' shown in FIG. 23. FIG. 26 is a cross sectional view taken 
along line F-F' shown in FIG. 23. Similar elements to those of the MR head 
according to the first embodiment are given the same reference numerals. 
As shown in FIGS. 23 to 26, the MR head according to this embodiment has a 
structure arranged such that magnetic layers 31 and 32 are formed at the 
two ends of the MR device portion 5 formed by laminating the MR device 3 
on the biasing conductor 4, that is, below the first conductors 6 and 7. 
Each of the magnetic layers 31 and 32 has a triple-layered structure formed 
by laminating a conductive film having a thickness of about 10 nm and made 
of Cr, a ferromagnetic film made of hard magnetic material, such as a Co 
material, having a large coercive force and a conductive film made of Cr. 
The conductive film formed below the ferromagnetic film serves as the 
ground for the ferromagnetic film in order to enlarge the coercive force 
of the ferromagnetic film. The ferromagnetic film is formed to make the MR 
device to be single magnetic domain, the ferromagnetic film being made of, 
for example, a ferromagnetic alloy, such as Co--Cr, Co--Cr--Pt or 
Co--Ni--Pt. The conductive film formed on the ferromagnetic film is 
arranged to prevent oxidation of the ferromagnetic film during the process 
for forming the MR head. Moreover, the conductive film protects the 
ferromagnetic film from etching damage when the groove is formed in the 
insulating layer 10a which is formed on the magnetic layers 31 and 32. 
The MR head according to this embodiment has a structure similar to that of 
the MR head according to the first embodiment except for the 
above-mentioned structure having the magnetic layers 31 and 32. In the MR 
head according to this embodiment, the influences of the magnetic fields 
from the magnetic layers 31 and 32 makes the MR device 3 to be a single 
magnetic domain so that generation of Barkhausen noise attributable to 
movement of the magnetic domain wall in the MR device 3 is prevented. 
Since the magnetic layers 31 and 32 have conductivity, the sense electric 
currents are, in the MR head, supplied from the first conductors 6 and 7 
to the MR device portion 5 through the magnetic layers 31 and 32. 
Therefore, the portion for effectively detecting the magnetic field from 
the recording medium is, in the MR device portion 5, the portion between 
the magnetic layer 31 and the magnetic layer 32. That is, the MR head is 
structured such that the distance T2 between the magnetic layer 31 and the 
magnetic layer 32 is the width of the track. Therefore, the width of the 
track is limited by the magnetic layers 31 and 32. 
A method of manufacturing the MR head having the above-mentioned structure 
will now be described with reference to FIGS. 27 to 29. FIGS. 27 to 29 
show the state of the cross section taken along line D-D' shown in FIG. 23 
in the sequential order of the manufacturing processes. The method of 
manufacturing the MR head according to this embodiment is similar to that 
for manufacturing the MR head according to the first embodiment except for 
an arrangement in which the magnetic layers 31 and 32 are formed prior to 
forming the first conductors 6 and 7. 
When the MR head according to this embodiment is manufactured, the 
insulating layer 2 is formed on the first soft magnetic substrate 1, and 
then the MR device portion 5 is formed on the insulating layer 2, 
similarly to the first embodiment. In this embodiment, the above-mentioned 
magnetic layers 31 and 32 are formed at the two ends of the portions which 
are formed into the magnetism sensing portions of the MR device portion 5, 
as shown in FIG. 27. As described above, the distance T2 between the 
magnetic layer 31 and the magnetic layer 32 is the width of the track of 
the MR head. Therefore, the magnetic layers 31 and 32 are formed in such a 
manner that the distance from the magnetic layer 31 to the magnetic layer 
32 is made to be a required width for the track. 
Then, as shown in FIG. 28, the insulating layer 10a made of Al.sub.2 
O.sub.3 or SiO.sub.2 is formed on the insulating layer 2, the MR device 
portion 5 and the magnetic layers 31 and 32 to have a thickness of about 
0.1 .mu.m. Note that the insulating layer 10a may be made of insulating 
material, such as NiO, having antiferromagnetism. 
Then, two grooves are formed in the insulating layer 10a in a direction 
substantially perpendicular to the direction in which the medium slides in 
such a manner that portions of the magnetic layers 31 and 32 are exposed. 
The grooves are formed as shown in FIG. 29 such that a resist 20 having an 
inversely tapered openings corresponding to the grooves is formed on the 
insulating layer 10a and then the resist 20 is used as a mask when the 
insulating layer 10a is etched by ion milling or the like. The uppermost 
layer of each of the magnetic layers 31 and 32 is a conductive film made 
of Cr. These conductive films protect the ferromagnetic films in the 
magnetic layers 31 and 32. Therefore, the ferromagnetic films in the 
magnetic layers 31 and 32 are not damaged during the above-mentioned 
etching process. 
If the MR device portion 5 is damaged during the etching process, it is 
made to be magnetically instable and Barkhausen noise is generated when 
the magnetoresistance effect magnetic head is operated. Therefore, when 
the above-mentioned grooves are formed, the opening, which is formed in 
the resist 20, is formed to have a width smaller than the width of each of 
the magnetic layers 31 and 32 in order to prevent exposure of the MR 
device portion 5. When the structure is arranged such that the MR device 
portion 5 is not exposed, the MR device portion 5 can be protected from 
etching damage during the process for etching the insulating layer 10a. As 
a result, generation of Barkhausen noise attributable to the etching 
damage can be prevented. 
Then, a process similar to that according to the first embodiment is 
performed so that the MR head according to this embodiment is 
manufactured. 
As can be understood from the foregoing description, the structure 
according to the present invention in which the conductor connected to the 
magnetoresistance effect magnetic device is embedded in the insulating 
layer enables the shield gap distance to be shortened. Therefore, 
according to the present invention, a MR head having an excellent 
frequency characteristic and capable of preventing generation of noise can 
be provided. 
Since the present invention has the structure arranged such that the 
conductor connected to the magnetoresistance effect magnetic device is 
embedded in the insulating layer, the process for etching the insulating 
layer formed on the conductor is not required when the shield gap distance 
is attempted to be shortened. That is, the present invention is able to 
reduce the number of processes for manufacturing the MR head even if the 
shield gap distance is shortened. Therefore, the present invention enables 
a MR head having a satisfactory frequency characteristic and capable of 
preventing generation of noise to be manufactured with a low cost. 
Although the invention has been described in its preferred form with a 
certain degree of particularity, it is understood that the present 
disclosure of the preferred form can be changed in the details of 
construction and in the combination and arrangement of parts without 
departing from the spirit and the scope of the invention as hereinafter 
claimed.