Planar thin-film magnetic head and manufacturing method therefor

A planar thin-film magnetic head including a lower magnetic pole having a first end portion and a second end portion, and an upper magnetic pole having a first end portion magnetically joined to the first end portion of the lower magnetic pole and a second end portion. A gap is defined between the second end portion of the lower magnetic pole and the second end portion of the upper magnetic pole. The thin-film magnetic head further includes a coil having a center positioned in the vicinity of the gap and spirally formed so as to pass between the upper magnetic pole and the lower magnetic pole. The coil is embedded in an insulating layer.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a planar thin-film magnetic head and a 
manufacturing method therefor. 
2. Description of the Related Art 
In recent years, a reduction in size and an increase in capacity of a 
magnetic disk drive as a kind of external storage device for a computer 
have been desired. In response thereto, the flying height of a magnetic 
head slider from a magnetic disk surface in recording and reproducing 
information is increasingly reduced, and the magnetic head slider is 
required to ensure stability and reliability at a low flying height and is 
also required to have a reduced weight. 
In general, a magnetic head slider used in a magnetic disk drive has a 
structure such that a vertical-structure type thin-film magnetic head is 
located on an rear end surface (air outlet end surface) of the slider 
perpendicular to a flying surface (medium opposing surface) of the slider. 
As a result, the height (thickness) of the slider is necessarily increased 
by the height of the vertically located thin-film magnetic head, and it is 
therefore greatly difficult to realize a compact, light magnetic head 
slider. To cope with this, there has been proposed a planar thin-film 
magnetic head slider having a thin-film magnetic head horizontally located 
on the medium opposing surface to thereby reduce the height of the 
magnetic head slider. 
FIG. 1 shows a schematic structure of a conventional planar thin-film 
magnetic head proposed in Japanese Patent Laid-open Nos. 3-127308 and 
6-4829, for example. Referring to FIG. 1, a gap 10 for generating a signal 
magnetic field in a recording medium 16 is defined in a lower magnetic 
pole 2. The lower magnetic pole 2 is connected to an upper magnetic pole 4 
by a pair of back closures 6 and 8, thus being magnetically closed. 
A pair of spiral coils 12 and 14 for generating a signal magnetic field are 
located about the back closures 6 and 8, respectively. As shown in FIG. 1, 
the gap 10 in the conventional planar thin-film magnetic head is normal to 
the recording medium 16. 
In the conventional planar thin-film magnetic head, the spiral coils 12 and 
14 are located so that the back closures 6 and 8 become the centers of the 
coils 12 and 14, respectively. Accordingly, the sectional area of each 
back closure is limited by the area of a central portion of each coil, so 
that it is impossible to ensure a large sectional area of each back 
closure. As a result, the magnetic resistance of the back closures 6 and 8 
is increased to cause a decrease in strength of the signal magnetic field 
at the back closures 6 and 8. Further, since the gap in the conventional 
planar thin-film magnetic head is normal to the recording medium, it is 
difficult to form a gap having a narrow width (0.3 .mu.m or less). 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a planar 
thin-film magnetic head which can reduce the magnetic resistance of a 
magnetic circuit to output a sufficiently strong recording signal magnetic 
field. 
It is another object of the present invention to provide a manufacturing 
method for a planar thin-film magnetic head which can easily achieve 
formation of a narrow gap. 
In accordance with an aspect of the present invention, there is provided a 
planar thin-film magnetic head comprising a lower magnetic pole having a 
first end portion and a second end portion; an upper magnetic pole having 
a first end portion magnetically joined to said first end portion of said 
lower magnetic pole and a second end portion; a gap defined between said 
second end portion of said lower magnetic pole and said second end portion 
of said upper magnetic pole; a coil having a center positioned in the 
vicinity of said gap and spirally formed so as to pass between said upper 
magnetic pole and said lower magnetic pole; and an insulating layer in 
which said coil is embedded. 
Preferably, the planar thin-film magnetic head according to the present 
invention further comprises a protective layer defining a medium opposing 
surface. The lower magnetic pole is laminated on the protective layer. The 
width of the gap is defined by the thickness of a dielectric film. 
In accordance with another aspect of the present invention, there is 
provided a manufacturing method for a planar thin-film magnetic head, 
comprising the steps of forming a lower magnetic pole on a sacrifice 
layer; forming a first insulating layer on said lower magnetic pole and 
said sacrifice layer except a part of said lower magnetic pole; forming a 
spiral coil on said first insulating layer so that the center of said 
spiral coil is positioned on said part of said lower magnetic pole; 
forming a second insulating layer on said spiral coil; forming a first 
mask resist for patterning said lower magnetic pole on said second 
insulating layer; etching off a portion of said lower magnetic pole 
unmasked by said first mask resist; forming a gap layer having a given 
thickness on the entire surface; forming a second mask resist for etching 
said gap layer on said gap layer; etching off a portion of said gap layer 
unmasked by said second mask resist; removing said second mask resist; 
forming an upper magnetic pole layer on the entire surface; forming a 
third mask resist for patterning said upper magnetic pole layer on said 
upper magnetic pole layer; etching off a portion of said upper magnetic 
pole layer unmasked by said third mask resist to form an upper magnetic 
pole; and removing said third mask resist. 
The above and other objects, features and advantages of the present 
invention and the manner of realizing them will become more apparent, and 
the invention itself will best be understood from a study of the following 
description and appended claims with reference to the attached drawings 
showing some preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 2, there is shown a perspective view of a magnetic disk 
drive in which a planar thin-film magnetic head according to the present 
invention is mounted. Reference numeral 42 denotes a housing (disk 
enclosure) consisting of a base 44 and a cover 46. A spindle hub (not 
shown) rotatably driven by an inner hub motor is provided on the base 44. 
A plurality of magnetic disks 50 and spacers (not shown) are mounted on 
the spindle hub in such a manner as to be alternately stacked. That is, 
the plural magnetic disks 50 are fixedly mounted on the spindle hub by 
securing a disk clamp 48 to the spindle hub by screws, and are equally 
spaced a given distance by the spacers. 
Reference numeral 52 denotes a rotary actuator consisting of an actuator 
arm assembly 56 and a magnetic circuit 58. The actuator arm assembly 56 is 
mounted so as to be rotatable about a shaft 54 fixed to the base 44. The 
actuator arm assembly 56 includes a plurality of actuator arms 60 
extending from the center of rotation in one direction and a coil 
supporting member 66 extending from the center of rotation in a direction 
opposite to the direction of extension of the actuator arms 60. 
A suspension 64 is fixed at its base end portion to a front end portion of 
each actuator arm 60. A magnetic head slider 62 is supported to a front 
end portion of the suspension 64. The magnetic head slider 62 is 
integrally formed with a planar thin-film magnetic head according to the 
present invention to be hereinafter described. A coil 68 is supported by 
the coil supporting member 66. The magnetic circuit 58 and the coil 68 
inserted in a gap of the magnetic circuit 58 constitute a voice coil motor 
(VCM) 70. 
Reference numeral 72 denotes a flexible printed circuit board (FPC) for 
taking a signal from the planar thin-film magnetic head mounted on the 
head slider 62. The flexible printed circuit board 72 is fixed at its one 
end by a fixing member 74, and is electrically connected to a connector 
(not shown). An annular packing assembly 76 is mounted on the base 44. The 
housing 42 is sealed by securing the cover 46 through the packing assembly 
76 to the base 44 by screws. 
Referring to FIG. 3A, there is shown a perspective view of the magnetic 
head slider 62 integrally formed with the planar thin-film magnetic head 
according to the present invention. FIG. 3B is a bottom plan view of FIG. 
3A. The magnetic head slider 62 has a pair of flying rails 63 and 65. A 
planar thin-film magnetic head 20 is formed on a flying surface (air 
bearing surface) of the flying rail 63. Actually, the magnetic head 20 is 
embedded in the flying rail 63, and only a gap 23 is exposed to the flying 
surface of the flying rail 63. Reference numeral 51 denotes a track of the 
magnetic disk 50. 
Referring to FIG. 4, there is shown a plan view of the magnetic head 20 
shown in FIG. 3. FIG. 5 is a cross section taken along the line 5--5 in 
FIG. 4. Reference numeral 22 denotes a protective layer of SiO.sub.2, 
which defines a medium opposing surface. The protective layer 22 has a 
thickness of about 2 to 3 m. A lower magnetic pole 24 having a thickness 
of about 1 m is laminated on the protective layer 22. The lower magnetic 
pole 24 is formed of FeNZr, Ni-Fe, or the like. Reference numeral 26 
denotes an upper magnetic pole having a thickness of about 1 m. Like the 
lower magnetic pole 24, the upper magnetic pole 26 is formed of FeNZr, 
Ni-Fe, or the like. 
One end portion 24a of the lower magnetic pole 24 and one end portion 26a 
of the upper magnetic pole 26 are magnetically joined to form a back 
closure 28. A gap 30 is defined between the other end portion 24b of the 
lower magnetic pole 24 and the other end portion 26b of the upper magnetic 
pole 26. A hole 23 is formed through the protective layer 22 at a position 
opposed to the gap 30. Reference numeral 32 denotes a spiral coil. The 
center of the spiral coil 32 is positioned in the vicinity of the gap 30, 
and the spiral coil 32 is so formed as to pass between the lower magnetic 
pole 24 and the upper magnetic pole 26. The spiral coil 32 has a film 
thickness of about 2 to 3 m. 
The spiral coil 32 is embedded in a resist insulating layer 34. A gap layer 
36 of a dielectric such as SiO.sub.2 and Al.sub.2 O.sub.3 is laminated on 
the resist insulating layer 34. The gap layer 36 has a thickness of about 
0.2 m. The width of the gap 30 is defined by the thickness of the 
dielectric gap layer 36. As apparent from FIG. 4, the back closure 28 as a 
joined portion between the lower magnetic pole 24 and the upper magnetic 
pole 26 has a large horizontally sectional area. Accordingly, the magnetic 
resistance of a magnetic circuit can be reduced to thereby prevent a 
recording signal magnetic field from being weakened at the back closure 
28. Furthermore, since the center of the coil 32 is positioned in the 
vicinity of the gap 30, the gap 30 falls in a maximum magnetic field 
region, thereby increasing the output of a recording signal magnetic 
field. 
A manufacturing method according to the present invention will now be 
described with reference to FIGS. 6A to 6N. 
As shown in FIG. 6A, a protective layer 22 of SiO.sub.2 is first laminated 
on a sacrifice layer 21 of Si, for example. The protective layer 22 has a 
thickness of about 2 to 3 .mu.m. In forming the protective layer 22, a 
hole 23 is formed at a position opposed to a gap 30 to be formed later. As 
shown in FIG. 6B, a lower magnetic pole 24 is formed on the protective 
layer 22 and patterned to a given shape. The lower magnetic pole 24 is 
formed of FeNZr, for example, and has a thickness of about 1 .mu.m. 
As shown in FIG. 6C, a first resist insulating layer 25 is formed on the 
protective layer 22 and the lower magnetic pole 24 and patterned to a 
given shape. The first resist insulating layer 25 has a thickness of about 
2 to 3 .mu.m. A spiral coil 32 having a film thickness of about 2 to 3 
.mu.m is formed on the first resist insulating layer 25, and a second 
resist insulating layer 27 is formed on the spiral coil 32 and patterned 
to a given shape. The second resist insulating layer 27 has a thickness of 
about 2 to 3 .mu.m. 
As shown in FIG. 6D, a mask resist 29 for patterning the lower magnetic 
pole 24 is formed on the second resist insulating layer 27 and patterned 
to a given shape. Then, a portion of the lower magnetic pole 24 unmasked 
by the mask resist 29 is etched off by ion milling (FIG. 6E). As shown in 
FIG. 6F, a dielectric gap layer 36 having a thickness (about 0.2 .mu.m) 
corresponding to a desired gap width is formed on the entire surface. The 
dielectric gap layer 36 is formed of SiO.sub.2, Al.sub.2 O.sub.3, or the 
like. 
As shown in FIG. 6G, a mask resist 33 for etching the gap layer 36 is 
formed on the gap layer 36 and patterned to a given shape. Then, a portion 
of the gap layer 36 unmasked by the mask resist 33 is etched off by ion 
milling (FIG. 6H). The etching by ion milling may be replaced by chemical 
etching. As shown in FIG. 6I, the mask resist 33 is removed, and as shown 
in FIG. 6J, an upper magnetic pole layer 26' having a thickness of about 1 
.mu.m is next formed on the entire surface. The upper magnetic pole layer 
26' is formed of FeNZr, for example. 
As shown in FIG. 6K, a mask resist 35 for patterning the upper magnetic 
pole layer 26' is formed on the upper magnetic pole layer 26' and 
patterned to a given shape. Then, a portion of the upper magnetic pole 
layer 26' unmasked by the mask resist 35 is etched off by ion milling to 
form an upper magnetic pole 26 as shown in FIG. 6L. As shown in FIG. GM, 
the mask resist 35 is removed, and as shown in FIG. 6N, the sacrifice 
layer 21 is removed to finally complete a planar thin-film magnetic head 
20. 
Although not specifically shown, the planar thin-film magnetic head 20 may 
be mounted on the slider, for example, by plating nickel on the SiO.sub.2 
protective layer 22 except the magnetic head 20 to form the slider into a 
given shape. 
According to the present invention, it is possible to provide a planar 
thin-film magnetic head which can reduce the magnetic resistance of a 
magnetic circuit to thereby increase the output of a recording signal 
magnetic field. Furthermore, a narrow gap can be easily formed because the 
gap width is defined by the thickness of the dielectric gap layer.