# Patent

## Title
Magnetic head for perpendicular magnetic recording including two side shields and main pole including lower protrusion

## Abstract

A first side shield has a first sidewall and a second sidewall. A second side shield has a third sidewall and a fourth sidewall. The distance between the first sidewall and the third sidewall decreases with increasing proximity to the top surface of a substrate. The second and fourth sidewalls are close to perpendicular to the top surface of the substrate. Each of the second and fourth sidewalls has an edge farthest from the top surface of the substrate, the edge being parallel to the medium facing surface. The main pole has a first, a second, a third and a fourth side surface. The first side surface is opposed to the first sidewall. A portion of the second side surface is opposed to the second sidewall. The third side surface is opposed to the third sidewall. A portion of the fourth side surface is opposed to the fourth sidewall.

## Background
This is a Continuation-in-Part of U.S. patent application Ser. No. 14/319,681 filed Jun. 30, 2014. The disclosure of the prior application is hereby incorporated by reference herein in its entirety.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic head for perpendicular magnetic recording that is used for writing data on a recording medium by means of a perpendicular magnetic recording system, and more specifically, to a magnetic head for perpendicular magnetic recording that has two side shields.
2. Description of the Related Art
The recording systems of magnetic read/write apparatuses include a longitudinal magnetic recording system wherein signals are magnetized in a direction along the plane of a recording medium (the longitudinal direction) and a perpendicular magnetic recording system wherein signals are magnetized in a direction perpendicular to the plane of a recording medium. It is known that the perpendicular magnetic recording system is harder to be affected by thermal fluctuation of the recording medium and capable of providing higher linear recording density when compared with the longitudinal magnetic recording system.
Magnetic heads for perpendicular magnetic recording typically have, like those for longitudinal magnetic recording, a structure in which a read head unit having a magnetoresistive element (hereinafter, also referred to as MR element) for reading and a write head unit having an induction-type electromagnetic transducer for writing are stacked on the top surface of a substrate. The write head unit includes a main pole configured to produce a write magnetic field in the direction perpendicular to the plane of the recording medium. The main pole has an end face that is located in a medium facing surface configured to face the recording medium.
The main pole includes, for example, a track width defining portion having an end located in the medium facing surface, and a wide portion connected to the other end of the track width defining portion. The track width defining portion has a top surface having a width smaller than that of the top surface of the wide portion. The width of the top surface of the track width defining portion in the medium facing surface defines the track width. To achieve higher recording densities, the track width should be as small as possible. Here, the length of the track width defining portion in the direction perpendicular to the medium facing surface will be referred to as the neck height. To improve the write characteristics of the write head unit, such as the overwrite property which indicates the overwriting capability, the neck height should be as small as possible.
A magnetic head for use in a magnetic disk drive such as a hard disk drive is typically in the form of a slider. The slider has the medium facing surface. The medium facing surface has an air inflow end (a leading end) and an air outflow end (a trailing end). The slider is designed to slightly fly over the surface of the recording medium by means of an airflow that comes from the leading end into the space between the medium facing surface and the recording medium.
Here, the side of the positions closer to the leading end relative to a reference position will be defined as the leading side, and the side of the positions closer to the trailing end relative to the reference position will be defined as the trailing side. The leading side is the rear side in the direction of travel of the recording medium relative to the slider. The trailing side is the front side in the direction of travel of the recording medium relative to the slider.
The magnetic head is typically disposed near the trailing end of the medium facing surface of the slider. In a magnetic disk drive, positioning of the magnetic head is performed by a rotary actuator, for example. In this case, the magnetic head moves over the recording medium along a circular orbit about the center of rotation of the rotary actuator. In such a magnetic disk drive, a tilt of the magnetic head with respect to the tangent of the circular track, which is called a skew, occurs depending on the position of the magnetic head across the tracks.
In particular, in a magnetic disk drive of the perpendicular magnetic recording system which is higher in capability of writing on a recording medium than the longitudinal magnetic recording system, the skew can cause the phenomenon that signals already written on one or more tracks in the neighborhood of a track targeted for writing are erased or attenuated during writing of a signal on the track targeted for writing. In the present application, this phenomenon will be called unwanted erasure. Unwanted erasure includes adjacent track erasure (ATE) and wide-area track erasure (WATE). To achieve higher recording densities, it is necessary to prevent unwanted erasure.
A known technique for preventing unwanted erasure induced by the skew is to shape the main pole such that its end face located in the medium facing surface has a width that decreases with increasing proximity to the top surface of the substrate, as disclosed in U.S. Pat. Nos. 8,270,110 B2 and 8,289,649 B2, for example.
U.S. Pat. Nos. 8,270,110 B2 and 8,289,649 B2 also disclose other effective techniques for preventing unwanted erasure induced by the skew. One of such techniques is to provide two side shields on opposite sides of the main pole in the track width direction, and another one is to provide a shield having an end face that is located in the medium facing surface and wraps around the end face of the main pole (such a shield will hereinafter be referred to as a wrap-around shield). The wrap-around shield includes a bottom shield located on the air-inflow-end side relative to the main pole, a top shield located on the air-outflow-end side relative to the main pole, and two side shields located on opposite sides of the main pole in the track width direction. These techniques allow for capturing a magnetic flux that is produced from the end face of the main pole and spreads in the track width direction. Thus, the occurrence of unwanted erasure can be prevented by these techniques.
A main pole of such a shape that its end face located in the medium facing surface has a width that decreases with increasing proximity to the top surface of the substrate suffers a problem as described below. If a main pole of such a shape is formed by a conventional method of forming a main pole, major part of the side surface of the main pole along the entire perimeter of the main pole will be formed into a slope inclined relative to a direction perpendicular to the top surface of the substrate. In such a case, the main pole has a smaller cross-sectional area perpendicular to the direction in which magnetic flux flows, when compared with a case where the entire side surface of the main pole is perpendicular to the top surface of the substrate. The main pole of the foregoing shape is unable to allow much magnetic flux to pass therethrough, especially through a portion near the boundary between the track width defining portion and the wide portion wider than the track width defining portion, and as a result, will cause degradation of write characteristics such as overwrite property.
An effective technique for solving the foregoing problem is, as disclosed in U.S. Pat. No. 8,289,649 B2, to form the main pole into the following particular shape. The main pole formed by the technique disclosed therein has six side surfaces: first and second side surfaces that are opposite to each other and located in a first region extending from the medium facing surface to a position at a predetermined distance from the medium facing surface; third and fourth side surfaces that are located in a second region other than the first region; a fifth side surface located in the boundary between the first and second regions and connecting the first side surface and the third side surface; and a sixth side surface located in the boundary between the first and second regions and connecting the second side surface and the fourth side surface. The distance between the first side surface and the second side surface in the track width direction decreases with increasing proximity to the top surface of the substrate. In the boundary between the first region and the second region, the distance between the third side surface and the fourth side surface in the track width direction when seen at the position closest to the top surface of the substrate is greater than the distance between the first side surface and the second side surface in the track width direction when seen at the position closest to the top surface of the substrate. Each of the fifth and sixth side surfaces has a width that increases with increasing proximity to the top surface of the substrate. This technique allows the main pole to have a large cross-sectional area perpendicular to the direction of flow of magnetic flux in the vicinity of the boundary between the track width defining portion and the wide portion, so that much magnetic flux can pass therethrough. This makes it possible to improve the write characteristics such as the overwrite property.
In the magnetic head disclosed in U.S. Pat. No. 8,289,649 B2, the distance between two main-pole-facing sidewalls of the two side shields gradually increases with increasing distance from the medium facing surface. In this structure, the cross-sectional area of the main pole in the vicinity of the medium facing surface is limited by the distance between the aforementioned two sidewalls of the two side shields. This structure thus has the drawback of being unable to sufficiently increase the cross-sectional area of the main pole in the vicinity of the medium facing surface.
OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a magnetic head for perpendicular magnetic recording that includes a main pole and two side shields, the magnetic head achieving improvement in write characteristics and prevention of unwanted erasure at the same time and allowing for a sufficient increase in the cross-sectional area of the main pole in the vicinity of the medium facing surface, and to provide a manufacturing method for such a magnetic head.
A magnetic head for perpendicular magnetic recording of the present invention includes: a medium facing surface configured to face a recording medium; a coil; a main pole; a write shield formed of a magnetic material; a gap part; and a substrate having a top surface. The coil is configured to produce a magnetic field corresponding to data to be written on the recording medium. The main pole is configured to allow a magnetic flux corresponding to the magnetic field produced by the coil to pass, and configured to produce a write magnetic field for writing data on the recording medium by means of a perpendicular magnetic recording system. The gap part is formed of a nonmagnetic material and provided between the main pole and the write shield. The coil, the main pole, the write shield and the gap part are disposed above the top surface of the substrate.
The write shield includes a first side shield and a second side shield located on opposite sides of the main pole in the track width direction. The first side shield has a first end face located in the medium facing surface, and has a first sidewall and a second sidewall facing the main pole. The second side shield has a second end face located in the medium facing surface, and has a third sidewall and a fourth sidewall facing the main pole. The first sidewall is connected to the first end face. The second sidewall is located farther from the medium facing surface than is the first sidewall. The third sidewall is connected to the second end face. The fourth sidewall is located farther from the medium facing surface than is the third sidewall.
In any cross section intersecting the first and third sidewalls and parallel to the medium facing surface, the distance between the first sidewall and the third sidewall in the track width direction decreases with increasing proximity to the top surface of the substrate. The second sidewall forms a smaller angle with respect to a direction perpendicular to the top surface of the substrate than does the first sidewall. The fourth sidewall forms a smaller angle with respect to the direction perpendicular to the top surface of the substrate than does the third sidewall. Each of the second and fourth sidewalls has an edge farthest from the top surface of the substrate. The edge of each of the second and fourth sidewalls is parallel to the medium facing surface and located at a distance of 20 to 120 nm from the medium facing surface.
The main pole has an end face located in the medium facing surface, a top surface farthest from the top surface of the substrate, a bottom end opposite to the top surface, and a first, a second, a third and a fourth side surface. The end face of the main pole has a first side located at an end of the top surface of the main pole, and has a second side and a third side opposite to each other in the track width direction. The distance between the second side and the third side in the track width direction decreases with increasing proximity to the top surface of the substrate. The first side surface is connected to the second side. The second side surface is located farther from the medium facing surface than is the first side surface. The third side surface is connected to the third side. The fourth side surface is located farther from the medium facing surface than is the third side surface.
The first side surface is opposed to the first sidewalk A portion of the second side surface is opposed to the second sidewall. The third side surface is opposed to the third sidewalk A portion of the fourth side surface is opposed to the fourth sidewall. In any cross section intersecting the first and third side surfaces and parallel to the medium facing surface, the distance between the first side surface and the third side surface in the track width direction decreases with increasing proximity to the top surface of the substrate. The second side surface forms a smaller angle with respect to the direction perpendicular to the top surface of the substrate than does the first side surface. The fourth side surface forms a smaller angle with respect to the direction perpendicular to the top surface of the substrate than does the third side surface.
The gap part includes a first portion interposed between the first sidewall and the first side surface and between the second sidewall and the second side surface, and a second portion interposed between the third sidewall and the third side surface and between the fourth sidewall and the fourth side surface.
A manufacturing method for the magnetic head for perpendicular magnetic recording of the present invention includes: a step of forming a first initial side shield and a second initial side shield, the first initial side shield having the first sidewall, the second initial side shield having the third sidewall; an etching step of etching a portion of the first initial side shield and a portion of the second initial side shield so that the first initial side shield is provided with the second sidewall and the second initial side shield is provided with the fourth sidewall; a step of forming the first and second portions of the gap part after the etching step; a step of forming an initial main pole after the step of forming the first and second portions of the gap part; a step of forming the coil; and a step of forming the medium facing surface so that the first initial side shield becomes the first side shield, the second initial side shield becomes the second side shield, and the initial main pole becomes the main pole.
In the magnetic head for perpendicular magnetic recording and the manufacturing method for the same of the present invention, the main pole may further have a first connecting surface connecting the first side surface and the second side surface, and a second connecting surface connecting the third side surface and the fourth side surface. Each of the first and second connecting surfaces has a width that increases with increasing proximity to the top surface of the substrate.
In the magnetic head for perpendicular magnetic recording and the manufacturing method for the same of the present invention, the main pole may further have a fifth side surface connected to the second side surface, and a sixth side surface connected to the fourth side surface. The fifth side surface is located farther from the medium facing surface than is the second side surface. The sixth side surface is located farther from the medium facing surface than is the fourth side surface. The fifth side surface forms a smaller angle with respect to the direction perpendicular to the top surface of the substrate than does the first side surface. The sixth side surface forms a smaller angle with respect to the direction perpendicular to the top surface of the substrate than does the third side surface. The manufacturing method for the magnetic head for perpendicular magnetic recording of the present invention may further include a step of forming a mold having a first inner wall and a second inner wall that define the shapes of the fifth side surface and the sixth side surface of the main pole, respectively, the step of forming the mold being performed between the step of forming the first and second portions of the gap part and the step of forming the initial main pole.
In the magnetic head for perpendicular magnetic recording and the manufacturing method for the same of the present invention, the write shield may further include a bottom shield and a top shield. The bottom shield has an end face that is located in the medium facing surface at a position on the rear side in the direction of travel of the recording medium relative to the end face of the main pole. The top shield has an end face that is located in the medium facing surface at a position on the front side in the direction of travel of the recording medium relative to the end face of the main pole.
The manufacturing method for the magnetic head for perpendicular magnetic recording of the present invention may further include: a step of forming a planarization layer to cover a stack including the first and second initial side shields after the step of forming the first initial side shield and the second initial side shield and before the etching step; and a step of forming a mask on the planarization layer after the step of forming the planarization layer and before the etching step. In such a case, the etching step etches the planarization layer and the first and second initial side shields by using the mask. The planarization layer may include a first layer formed of a resin and a second layer formed of an inorganic material and lying on the first layer.
Where the write shield includes the bottom shield and the top shield, the main pole may include a main body and a lower protrusion, the lower protrusion protruding from the main body toward the top surface of the substrate. The lower protrusion is located at a distance from the medium facing surface. The main body includes a front portion and a rear portion, the front portion being located closer to the medium facing surface than is the lower protrusion, the rear portion being located farther from the medium facing surface than is the front portion. The front portion includes the end face of the main pole and the first and third side surfaces of the main pole. The rear portion includes the second and fourth side surfaces. The lower protrusion has a bottom surface, a first side portion and a second side portion, the bottom surface facing toward the top surface of the substrate, the first and second side portions being opposite to each other in the track width direction.
Where the main pole includes the main body and the lower protrusion, the magnetic head for perpendicular magnetic recording of the present invention may further include a return path section and a nonmagnetic layer. The return path section is formed of a magnetic material, located on the rear side in the direction of travel of the recording medium relative to the main pole, and connects the lower protrusion and the bottom shield to each other so that a space is defined by the main pole, the gap part, the bottom shield and the return path section. The return path section includes a connection layer in contact with the lower protrusion. The nonmagnetic layer is formed of a nonmagnetic material and disposed around the bottom shield and the connection layer. The bottom shield includes a first receiving section for receiving a portion of the lower protrusion. The nonmagnetic layer includes a second receiving section for receiving the remainder of the lower protrusion. The first receiving section has a bottom surface, a fifth sidewall and a sixth sidewall, the fifth sidewall being opposed to a portion of the first side portion, the sixth sidewall being opposed to a portion of the second side portion.
The first sidewall may have a first edge closest to the top surface of the substrate. The second sidewall may have a second edge closest to the top surface of the substrate. The fifth sidewall may have a third edge farthest from the top surface of the substrate. The sixth sidewall may have a fourth edge farthest from the top surface of the substrate. The third edge may be contiguous with the first edge. The fourth edge may be contiguous with the second edge. The entirety of the bottom surface of the lower protrusion may be inclined with respect to a direction perpendicular to the medium facing surface such that the lower protrusion gradually increases in thickness with increasing proximity to the connection layer.
The lower protrusion may be smaller in maximum thickness than the main body. The distance between the third edge and the fourth edge in the track width direction may increase with increasing distance from the medium facing surface. In any cross section intersecting the rear portion and parallel to the medium facing surface, the rear portion may have a greater width in the track width direction than that of the lower protrusion.
Where the main pole includes the main body and the lower protrusion, the manufacturing method for the magnetic head for perpendicular magnetic recording of the present invention may further include: a step of forming an initial bottom shield and an initial nonmagnetic layer before the step of forming the first initial side shield and the second initial side shield; a step of forming a planarization layer to cover a stack including the initial bottom shield, the initial nonmagnetic layer and the first and second initial side shields after the step of forming the first initial side shield and the second initial side shield and before the etching step; and a step of forming a mask on the planarization layer after the step of forming the planarization layer and before the etching step. In such a case, the etching step etches the planarization layer, the first and second initial side shields, the initial bottom shield and the initial nonmagnetic layer by using the mask so that the first and second receiving sections are formed. The planarization layer may include a first layer formed of a resin and a second layer formed of an inorganic material and lying on the first layer.
In the magnetic head for perpendicular magnetic recording and the manufacturing method for the same of the present invention, the main pole has the first to fourth side surfaces defined as above, and the write shield includes the first and second side shields. These features of the present invention make it possible to prevent unwanted erasure and achieve improved write characteristics at the same time. Further, the present invention allows for sufficiently increasing the cross-sectional area of the main pole in the vicinity of the medium facing surface, and consequently allows for further improvement in write characteristics.
Other and further objects, features and advantages of the present invention will appear more fully from the following description.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing part of a main pole and first and second side shields in the vicinity of a medium facing surface in a magnetic head according to a first embodiment of the invention.
FIG. 2 is a perspective view of part of the first and second side shields in the vicinity of the medium facing surface in the magnetic head according to the first embodiment of the invention.
FIG. 3 is a perspective view of part of the main pole in the vicinity of the medium facing surface in the magnetic head according to the first embodiment of the invention.
FIG. 4 is a plan view of part of the main pole and the first and second side shields in the vicinity of the medium facing surface in the magnetic head according to the first embodiment of the invention.
FIG. 5 is a front view showing respective end faces of the main pole and the first and second side shields located in the medium facing surface in the magnetic head according to the first embodiment of the invention.
FIG. 6 is a cross-sectional view showing the configuration of the magnetic head according to the first embodiment of the invention.
FIG. 7 is a front view showing the medium facing surface of the magnetic head according to the first embodiment of the invention.
FIG. 8 is a plan view showing a first portion of a coil of the magnetic head according to the first embodiment of the invention.
FIG. 9 is a plan view showing the main pole, the first side shield and the second side shield of the magnetic head according to the first embodiment of the invention.
FIG. 10 is a plan view showing a first layer of a second portion of the coil of the magnetic head according to the first embodiment of the invention.
FIG. 11 is a plan view showing a second layer of the second portion of the coil of the magnetic head according to the first embodiment of the invention.
FIG. 12 is a plan view showing the shape of a portion of a photomask to be used in a manufacturing method for the magnetic head according to the first embodiment of the invention.
FIG. 13 is a plan view showing a step of the manufacturing method for the magnetic head according to the first embodiment of the invention.
FIG. 14 is a cross-sectional view showing a step that follows the step of FIG. 13.
FIG. 15 is a cross-sectional view showing a step that follows the step of FIG. 14.
FIG. 16 is a cross-sectional view showing a step that follows the step of FIG. 15.
FIG. 17 is a cross-sectional view showing a step that follows the step of FIG. 16.
FIG. 18 is a plan view showing a step that follows the step of FIG. 17.
FIG. 19 is a plan view showing a step that follows the step of FIG. 18.
FIG. 20 is a plan view showing a step that follows the step of FIG. 19.
FIG. 21 is a plan view showing a step that follows the step of FIG. 20.
FIG. 22 is a plan view showing a step that follows the step of FIG. 21.
FIG. 23 is a plan view showing the step of forming the medium facing surface in the manufacturing method for the magnetic head according to the present embodiment of the invention.
FIG. 24 is a plan view showing part of a main pole and first and second side shields in the vicinity of a medium facing surface in a magnetic head of a comparative example.
FIG. 25 is a perspective view showing a main pole, a bottom shield, a first side shield and a second side shield of a magnetic head according to a second embodiment of the invention.
FIG. 26 is a perspective view of the main pole of the magnetic head according to the second embodiment of the invention.
FIG. 27 is a cross-sectional view showing the main part of the magnetic head according to the second embodiment of the invention.
FIG. 28 is a plan view showing the main pole, the first side shield and the second side shield of the magnetic head according to the second embodiment of the invention.
FIG. 29 is a perspective view showing the bottom shield, the first side shield, the second side shield and a nonmagnetic layer of the magnetic head according to the second embodiment of the invention.
FIG. 30 is a cross-sectional view of the magnetic head according to the second embodiment of the invention.
FIG. 31 is a front view showing the medium facing surface of the magnetic head according to the second embodiment of the invention.
FIG. 32 is a plan view showing a first portion of a coil of the magnetic head according to the second embodiment of the invention.
FIG. 33 is a plan view showing a second portion of the coil of the magnetic head according to the second embodiment of the invention.
FIG. 34A and FIG. 34B are explanatory diagrams showing a step of a manufacturing method for the magnetic head according to the second embodiment of the invention.
FIG. 35A and FIG. 35B are explanatory diagrams showing a step that follows the step shown in FIG. 34A and FIG. 34B.
FIG. 36A to FIG. 36D are explanatory diagrams showing a step that follows the step shown in FIG. 35A and FIG. 35B.
FIG. 37A to FIG. 37D are explanatory diagrams showing a step that follows the step shown in FIG. 36A to FIG. 36D.
FIG. 38A to FIG. 38D are explanatory diagrams showing a step that follows the step shown in FIG. 37A to FIG. 37D.
FIG. 39A and FIG. 39B are explanatory diagrams showing a step that follows the step shown in FIG. 38A to FIG. 38D.
FIG. 40A and FIG. 40B are explanatory diagrams showing a step that follows the step shown in FIG. 39A and FIG. 39B.
FIG. 41A and FIG. 41B are explanatory diagrams showing a step that follows the step shown in FIG. 40A and FIG. 40B.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
Preferred embodiments of the present invention will now be described in detail with reference to the drawings. First, reference is made to FIG. 6 to FIG. 11 to describe the configuration of a magnetic head according to a first embodiment of the invention. FIG. 6 is a cross-sectional view showing the configuration of the magnetic head according to the present embodiment. FIG. 6 shows a cross section perpendicular to the medium facing surface and to the top surface of the substrate. The arrow with the symbol T in FIG. 6 indicates the direction of travel of a recording medium. FIG. 7 is a front view showing the medium facing surface of the magnetic head according to the present embodiment. FIG. 8 is a plan view showing a first portion of a coil of the magnetic head according to the present embodiment. FIG. 9 is a plan view showing a main pole, a first side shield and a second side shield of the magnetic head according to the present embodiment. FIG. 10 is a plan view showing a first layer of a second portion of the coil of the magnetic head according to the present embodiment. FIG. 11 is a plan view showing a second layer of the second portion of the coil of the magnetic head according to the present embodiment. In each of FIG. 7 to FIG. 11, the arrow with the symbol TW indicates the track width direction.
As shown in FIG. 6, the magnetic head for perpendicular magnetic recording (hereinafter simply referred to as the magnetic head) according to the present embodiment has a medium facing surface 80 configured to face a recording medium 90. Further, as shown in FIG. 6 and FIG. 7, the magnetic head includes a substrate 1 formed of a ceramic material such as aluminum oxide-titanium carbide (Al2O3—TiC) and having a top surface 1a, an insulating layer 2 formed of an insulating material such as alumina (Al2O3) and disposed on the top surface 1a of the substrate 1, a first read shield layer 3 formed of a magnetic material and disposed on the insulating layer 2, a first read shield gap film 4 which is an insulating film disposed to cover the first read shield layer 3, a magnetoresistive (MR) element 5 serving as a read element disposed on the first read shield gap film 4, a second read shield gap film 6 which is an insulating film disposed on the MR element 5, and a second read shield layer 7 formed of a magnetic material and disposed on the second read shield gap film 6.
An end of the MR element 5 is located in the medium facing surface 80. The MR element 5 may be an element formed of a magneto-sensitive film that exhibits a magnetoresistive effect, such as an anisotropic magnetoresistive (AMR) element, a giant magnetoresistive (GMR) element, or a tunneling magnetoresistive (TMR) element. The GMR element may be of either the current-in-plane (CIP) type in which a current used for detecting magnetic signals is fed in a direction generally parallel to the planes of layers constituting the GMR element or the current-perpendicular-to-plane (CPP) type in which the current used for detecting magnetic signals is fed in a direction generally perpendicular to the planes of layers constituting the GMR element.
The parts from the first read shield layer 3 to the second read shield layer 7 constitute a read head unit 8. The magnetic head further includes a nonmagnetic layer 71 formed of a nonmagnetic material and disposed on the second read shield layer 7, a middle shield layer 72 formed of a magnetic material and disposed on the nonmagnetic layer 71, a nonmagnetic layer 73 formed of a nonmagnetic material and disposed on the middle shield layer 72, and a write head unit 9 disposed on the nonmagnetic layer 73. The middle shield layer 72 has the function of shielding the MR element 5 from magnetic fields generated in the write head unit 9. The nonmagnetic layers 71 and 73 are formed of alumina, for example.
The write head unit 9 includes a coil, a main pole 15, a write shield 16, and a gap part 17. The coil is configured to produce a magnetic field corresponding to data to be written on the recording medium 90. The coil includes a first portion 10 and a second portion 20. The first portion 10 and the second portion 20 are both formed of a conductive material such as copper. The first portion 10 and the second portion 20 are connected in series or in parallel. The main pole 15 has an end face 15a located in the medium facing surface 80. The main pole 15 is configured to allow a magnetic flux corresponding to the magnetic field produced by the coil to pass, and configured to produce a write magnetic field for writing data on the recording medium 90 by means of a perpendicular magnetic recording system. FIG. 6 shows a cross section that intersects the end face 15a of the main pole 15 and that is perpendicular to the medium facing surface 80 and to the top surface 1a of the substrate 1.
As shown in FIG. 7, the write shield 16 includes a first side shield 16A, a second side shield 16B, a bottom shield 16C, and a top shield 16D. The first and second side shields 16A and 16B are located on opposite sides of the main pole 15 in the track width direction TW. The bottom shield 16C is located on the rear side in the direction T of travel of the recording medium 90 relative to the main pole 15. The top shield 16D is located on the front side in the direction T of travel of the recording medium 90 relative to the main pole 15. The side shields 16A and 16B magnetically couple the bottom shield 16C and the top shield 16D to each other.
As shown in FIG. 7, the first side shield 16A has a first end face 16Aa located in the medium facing surface 80. The second side shield 16B has a second end face 16Ba located in the medium facing surface 80. As shown in FIG. 6 and FIG. 7, the bottom shield 16C has an end face 16Ca located in the medium facing surface 80, and a top surface 16Cb including an inclined portion. The distance from the top surface 1a of the substrate 1 to an arbitrary point on the inclined portion decreases with increasing distance from the arbitrary point to the medium facing surface 80. The top shield 16D has an end face 16Da located in the medium facing surface 80, a bottom surface, a top surface, and a connecting surface connecting the end face 16Da and the top surface. The distance from the top surface 1a of the substrate 1 to an arbitrary point on the bottom surface increases with increasing distance from the arbitrary point to the medium facing surface 80. The distance from the medium facing surface 80 to an arbitrary point on the connecting surface increases with increasing distance from the arbitrary point to the top surface 1a of the substrate 1.
The first and second end faces 16Aa and 16Ba are located on opposite sides of the end face 15a of the main pole 15 in the track width direction TW. The end face 16Ca is located on the rear side in the direction T of travel of the recording medium 90 relative to the end face 15a of the main pole 15. The end face 16Da is located on the front side in the direction T of travel of the recording medium 90 relative to the end face 15a of the main pole 15. In the medium facing surface 80, the end faces 16Aa, 16Ba, 16Ca and 16Da are arranged to wrap around the end face 15a of the main pole 15.
The write shield 16 is formed of a magnetic material. The material employed for the write shield 16 may be CoFeN, CoNiFe, NiFe, or CoFe, for example.
The write head unit 9 further includes magnetic layers 31 to 36 and 41 to 44. Each of the magnetic layers 31 to 36 and 41 to 44 is formed of a magnetic material. The material employed for each of the magnetic layers 31 to 36 and 41 to 44 may be CoFeN, CoNiFe, NiFe, or CoFe, for example. The magnetic layer 31 lies on the nonmagnetic layer 73. The magnetic layers 32 and 33 both lie on the magnetic layer 31. The magnetic layer 32 is located near the medium facing surface 80. The magnetic layer 33 is located farther from the medium facing surface 80 than is the magnetic layer 32. Each of the magnetic layers 31 and 32 has an end face that faces toward the medium facing surface 80 and that is located at a distance from the medium facing surface 80. As shown in FIG. 8, the first portion 10 of the coil is wound approximately four turns around the magnetic layer 33.
The magnetic head further includes: an insulating layer 51 formed of an insulating material, disposed on the nonmagnetic layer 73 and surrounding the magnetic layer 31; an insulating film 52 formed of an insulating material and isolating the first portion 10 from the magnetic layers 31 to 33; an insulating layer 53 formed of an insulating material and disposed in the space between adjacent turns of the first portion 10; and an insulating layer 54 formed of an insulating material and disposed around the first portion 10 and the magnetic layer 32. The top surfaces of the first portion 10, the magnetic layers 32 and 33, the insulating film 52 and the insulating layers 53 and 54 are even with each other. The insulating layers 51 and 54 and the insulating film 52 are formed of alumina, for example. The insulating layer 53 is formed of a photoresist, for example.
The magnetic layer 34 lies on the magnetic layer 32 and the insulating layer 54. The magnetic layer 35 lies on the magnetic layer 33. The magnetic layer 34 has an end face located in the medium facing surface 80. The magnetic head further includes: an insulating layer 55 formed of an insulating material and disposed over the top surfaces of the first portion 10, the insulating film 52 and the insulating layers 53 and 54; and an insulating layer 56 formed of an insulating material, disposed on the insulating layer 55 and surrounding the magnetic layers 34 and 35. The insulating layers 55 and 56 are formed of alumina, for example.
The bottom shield 16C lies on the magnetic layer 34. The magnetic layer 36 lies on the magnetic layer 35. The magnetic head further includes a nonmagnetic layer 57 formed of a nonmagnetic material. The nonmagnetic layer 57 lies on the top surface of the insulating layer 56 and part of the top surface of the magnetic layer 34, and surrounds the bottom shield 16C and the magnetic layer 36. The nonmagnetic layer 57 is formed of alumina, for example.
The first and second side shields 16A and 16B are disposed on the bottom shield 16C and in contact with the top surface 16Cb of the bottom shield 16C. The main pole 15 has a top surface 15T (see FIG. 6) farthest from the top surface 1a of the substrate 1, a bottom end 15L (see FIG. 6) opposite to the top surface 15T, and a plurality of side surfaces (see FIG. 9). Each of the first and second side shields 16A and 16B has a plurality of sidewalls. The plurality of side surfaces of the main pole 15 and the plurality of sidewalls of each of the first and second side shields 16A and 16B will be described in detail later.
As shown in FIG. 9, the main pole 15 may include: a track width defining portion 15A having an end face located in the medium facing surface 80 and an end opposite to the end face; and a wide portion 15B connected to the end of the track width defining portion 15A. In the track width defining portion 15A, the width of the top surface 15T in the track width direction TW may gradually increase with increasing distance from the medium facing surface 80 as shown in FIG. 9, or may be substantially constant regardless of distance from the medium facing surface 80. The width of the top surface 15T in the track width direction TW is greater in the wide portion 15B than in the track width defining portion 15A. The end face of the track width defining portion 15A located in the medium facing surface 80 also serves as the end face 15a of the main pole 15. The length of the ridge between the top surface 15T of the main pole 15 and the end face of the track width defining portion 15A located in the medium facing surface 80 defines the track width.
The gap part 17 is provided between the main pole 15 and the write shield 16. The magnetic head further includes a first gap layer 18 and a second gap layer 19. The first gap layer 18 is formed of a nonmagnetic material and includes a portion that forms a portion of the gap part 17. The second gap layer 19 is formed of a nonmagnetic material and includes a portion that forms another portion of the gap part 17. The aforementioned portion of the first gap layer 18 forming the portion of the gap part 17 is located between the main pole 15 and each of the side shields 16A and 16B and the bottom shield 16C. The aforementioned portion of the second gap layer 19 forming the other portion of the gap part 17 is located between the main pole 15 and the top shield 16D.
The first gap layer 18 is disposed along the plurality of sidewalls of each of the first and second side shields 16A and 16B, the top surface 16Cb of the bottom shield 16C and the top surface of the nonmagnetic layer 57. The nonmagnetic material used to form the first gap layer 18 may be an insulating material or a nonmagnetic metal material. Alumina is an example of an insulating material that can be used to form the first gap layer 18. Ru is an example of a nonmagnetic metal material that can be used to form the first gap layer 18. The first gap layer 18 has a thickness in the range of 40 to 100 nm, for example.
The main pole 15 is disposed over the bottom shield 16C and the nonmagnetic layer 57 such that the first gap layer 18 is interposed between the main pole 15 and each of the top surface 16Cb of the bottom shield 16C and the top surface of the nonmagnetic layer 57. As shown in FIG. 7, the first gap layer 18 is interposed also between the main pole 15 and each of the first and second side shields 16A and 16B.
At a position away from the medium facing surface 80, the bottom end 15L of the main pole 15 is in contact with the top surface of the magnetic layer 36. The main pole 15 is formed of a magnetic metal material. The material employed for the main pole 15 may be NiFe, CoNiFe, or CoFe, for example.
The magnetic head further includes a nonmagnetic layer 61 formed of a nonmagnetic material and disposed around the main pole 15 and the side shields 16A and 16B. The nonmagnetic layer 61 is shown in FIG. 1 and FIG. 4, which will be described later. In the present embodiment, the nonmagnetic layer 61 is formed of a nonmagnetic insulating material such as alumina, in particular.
The magnetic head further includes a nonmagnetic metal layer 58 formed of a nonmagnetic metal material, located away from the medium facing surface 80 and lying on part of the top surface 15T of the main pole 15, and an insulating layer 59 formed of an insulating material and lying on the top surface of the nonmagnetic metal layer 58. The nonmagnetic metal layer 58 is formed of Ru, NiCr, or NiCu, for example. The insulating layer 59 is formed of alumina, for example.
The second gap layer 19 is disposed to cover the main pole 15, the nomnagnetic metal layer 58 and the insulating layer 59. The material employed for the second gap layer 19 may be a nonmagnetic insulating material such as alumina or a nonmagnetic conductive material such as Ru, NiCu, Ta, W, NiB, or NiP.
The top shield 16D is disposed over the side shields 16A and 16B and the second gap layer 19, and in contact with the top surfaces of the side shields 16A and 16B and the second gap layer 19. In the medium facing surface 80, part of the end face 16Da of the top shield 16D is spaced from the end face 15a of the main pole 15 by a predetermined distance created by the thickness of the second gap layer 19. The thickness of the second gap layer 19 preferably falls within the range of 5 to 60 nm, and may be 30 to 60 nm, for example.
The magnetic layer 41 is located away from the medium facing surface 80 and lies on the main pole 15. The second portion 20 of the coil includes a first layer 21 and a second layer 22. As shown in FIG. 10, the first layer 21 is wound one turn around the magnetic layer 41. The magnetic head further includes an insulating film 62 formed of an insulating material and isolating the first layer 21 from the top shield 16D, the second gap layer 19 and the magnetic layer 41, and a first nonmagnetic layer (not illustrated) formed of a nonmagnetic material and disposed around the first layer 21 and the top shield 16D. The insulating film 62 and the first nonmagnetic layer are formed of alumina, for example. The top surfaces of the top shield 16D, the first layer 21, the magnetic layer 41, the insulating film 62 and the first nonmagnetic layer are even with each other.
The magnetic head further includes an insulating layer 63 formed of an insulating material and disposed over the top surfaces of the first layer 21 and the insulating film 62. The insulating layer 63 is formed of alumina, for example.
The magnetic layer 42 lies on the top shield 16D and the insulating layer 63. The magnetic layer 42 has an end face that faces toward the medium facing surface 80 and that is located at a distance from the medium facing surface 80. The distance from the medium facing surface 80 to an arbitrary point on the end face of the magnetic layer 42 increases with increasing distance from the arbitrary point to the top surface 1a of the substrate 1.
The magnetic layer 43 lies on the magnetic layer 41. As shown in FIG. 11, the second layer 22 is wound approximately one turn around the magnetic layer 43. The magnetic head further includes an insulating film 64 formed of an insulating material and isolating the second layer 22 from the magnetic layers 42 and 43 and the insulating layer 63, and a second nonmagnetic layer (not illustrated) formed of a nonmagnetic material and disposed around the second layer 22 and the magnetic layer 42. The insulating film 64 and the second nonmagnetic layer are formed of alumina, for example. The top surfaces of the second layer 22, the magnetic layers 42 and 43, the insulating film 64 and the second nonmagnetic layer are even with each other. The magnetic head further includes an insulating layer 65 formed of an insulating material and disposed over the top surfaces of the second layer 22 and the insulating film 64. The insulating layer 65 is formed of alumina, for example.
The magnetic layer 44 lies on the magnetic layers 42 and 43 and the insulating layer 65, and connects the magnetic layer 42 and the magnetic layer 43. The magnetic layer 44 has an end face that faces toward the medium facing surface 80 and that is located at a distance from the medium facing surface 80. The distance from the medium facing surface 80 to an arbitrary point on the end face of the magnetic layer 44 increases with increasing distance from the arbitrary point to the top surface 1a of the substrate 1.
The magnetic head further includes a nonmagnetic layer 66 formed of a nonmagnetic material and disposed around the magnetic layer 44, and a protective layer 70 formed of a nonmagnetic material and disposed to cover the write head unit 9. Part of the nonmagnetic layer 66 is interposed between the medium facing surface 80 and each of the connecting surface of the top shield 16D and the respective end faces of the magnetic layers 42 and 44 facing toward the medium facing surface 80. The nonmagnetic layer 66 and the protective layer 70 are formed of alumina, for example.
As has been described, the magnetic head according to the present embodiment includes the medium facing surface 80, the read head unit 8, and the write head unit 9. The read head unit 8 and the write head unit 9 are stacked on the substrate 1. The read head unit 8 is located on the rear side in the direction T of travel of the recording medium 90, i.e., the leading side, relative to the write head unit 9.
The write head unit 9 includes the coil including the first and second portions 10 and 20, the main pole 15, the write shield 16, the gap part 17, and the magnetic layers 31 to 36 and 41 to 44. The coil, the main pole 15, the write shield 16, and the gap part 17 are disposed above the top surface 1a of the substrate 1. The write shield 16 includes the first side shield 16A, the second side shield 16B, the bottom shield 16C, and the top shield 16D. The gap part 17 is composed of part of the first gap layer 18 and part of the second gap layer 19.
The magnetic layers 31 to 36 are located on the rear side in the direction T of travel of the recording medium 90 relative to the main pole 15, and constitute a first return path section. As shown in FIG. 6, the first return path section (the magnetic layers 31 to 36) connects the write shield 16 and part of the main pole 15 located away from the medium facing surface 80 to each other so that a first space is defined by the main pole 15, the gap part 17 (the gap layer 18), the write shield 16 and the first return path section. The first portion 10 of the coil passes through the first space.
The magnetic layers 41 to 44 are located on the front side in the direction T of travel of the recording medium 90 relative to the main pole 15, and constitute a second return path section. The second return path section (the magnetic layers 41 to 44) connects the write shield 16 and part of the main pole 15 located away from the medium facing surface 80 to each other so that a second space is defined by the main pole 15, the gap part 17 (the gap layer 19), the write shield 16 and the second return path section. The second portion 20 of the coil passes through the second space.
The write shield 16 captures a disturbance magnetic field applied to the magnetic head from the outside thereof. This makes it possible to prevent the disturbance magnetic field from being intensively captured into the main pole 15 and thereby causing erroneous writing on the recording medium 90. The write shield 16 also has the function of capturing a magnetic flux that is produced from the end face 15a of the main pole 15 and spreads in directions other than the direction perpendicular to the plane of the recording medium 90, and thereby preventing the magnetic flux from reaching the recording medium 90. Furthermore, the write shield 16, the first return path section (the magnetic layers 31 to 36) and the second return path section (the magnetic layers 41 to 44) have the function of allowing a magnetic flux that has been produced from the end face 15a of the main pole 15 and has magnetized the recording medium 90 to flow back.
The first and second portions 10 and 20 of the coil will now be described in detail with reference to FIG. 8 to FIG. 11. FIG. 8 is a plan view showing the first portion 10. The first portion 10 is wound approximately four turns around the magnetic layer 33. The first portion 10 includes a portion that extends to pass between the magnetic layer 32 and the magnetic layer 33, in particular, within the first space. The first portion 10 has a coil connection 10E electrically connected to the second portion 20.
FIG. 10 is a plan view showing the first layer 21 of the second portion 20. The first layer 21 is wound one turn around the magnetic layer 41. The first layer 21 includes a portion that extends to pass between the top shield 16D and the magnetic layer 41, in particular, within the second space. The first layer 21 has a coil connection 21S electrically connected to the coil connection 10E of the first portion 10, and a coil connection 21E electrically connected to the second layer 22. The coil connection 21S is electrically connected to the coil connection 10E via a first, a second and a third connection layer 11, 12 and 13 of columnar shape (see FIG. 9) which penetrate a plurality of layers interposed between the first layer 21 and the first portion 10. The first to third connection layers 11, 12 and 13 are stacked in this order on the coil connection 10E. The coil connection 21S is disposed on the third connection layer 13. The first to third connection layers 11 to 13 are each formed of a conductive material such as copper.
FIG. 11 is a plan view showing the second layer 22 of the second portion 20. The second layer 22 is wound approximately one turn around the magnetic layer 43. The second layer 22 includes a portion that extends to pass between the magnetic layer 42 and the magnetic layer 43, in particular, within the second space. The second layer 22 has a coil connection 22S penetrating the insulating layer 63 and the insulating film 64 and electrically connected to the coil connection 21E of the first layer 21. In the example shown in FIG. 8 to FIG. 11, the first portion 10 and the second portion 20 are connected in series.
The main pole 15, the first side shield 16A and the second side shield 16B will now be described in detail with reference to FIG. 1 to FIG. 7. FIG. 1 is a perspective view showing part of the main pole 15 and the first and second side shields 16A and 16B in the vicinity of the medium facing surface 80. FIG. 2 is a perspective view of part of the first and second side shields 16A and 16B in the vicinity of the medium facing surface 80. FIG. 3 is a perspective view of part of the main pole 15 in the vicinity of the medium facing surface 80. FIG. 4 is a plan view of part of the main pole 15 and the first and second side shields 16A and 16B in the vicinity of the medium facing surface 80. FIG. 5 is a front view showing respective end faces of the main pole 15 and the first and second side shields 16A and 16B located in the medium facing surface 80.
As shown in FIG. 1, FIG. 2 and FIG. 4, the first side shield 16A has the first end face 16Aa located in the medium facing surface 80, and has a first sidewall SW1 and a second sidewall SW2 facing the main pole 15. The second side shield 16B has the second end face 16Ba located in the medium facing surface 80, and has a third sidewall SW3 and a fourth sidewall SW4 facing the main pole 15. The first sidewall SW1 is connected to the first end face 16Aa. The second sidewall SW2 is connected to the first sidewall SW1, and is located farther from the medium facing surface 80 than is the first sidewall SW1. The third sidewall SW3 is connected to the second end face 16Ba. The fourth sidewall SW4 is connected to the third sidewall SW3, and is located farther from the medium facing surface 80 than is the third sidewall SW3.
As shown in FIG. 2, in any cross section intersecting the first and third sidewalls SW1 and SW3 and parallel to the medium facing surface 80, the distance between the first sidewall SW1 and the third sidewall SW3 in the track width direction TW decreases with increasing proximity to the top surface 1a (see FIG. 6 and FIG. 7) of the substrate 1. Each of the first sidewall SW1 and the third sidewall SW3 forms an angle in the range of, for example, 7° to 17°, preferably in the range of 10° to 15°, with respect to a direction perpendicular to the top surface 1a of the substrate 1.
As shown in FIG. 2 and FIG. 4, the second and fourth sidewalls SW2 and SW4 have their respective edges E1 and E2 farthest from the top surface 1a of the substrate 1. The edges E1 and E2 are parallel to the medium facing surface 80. The edges E1 and E2 are located at an equal distance from the medium facing surface 80, the distance preferably falling within the range of 20 to 120 nm, more preferably within the range of 30 to 90 nm. Here, the distance from the medium facing surface 80 to each of the edges E1 and E2 will be defined as the side shield height SH, and an edge of the top surface of each of the side shields 16A and 16B that faces the main pole 15 will be referred to as the pole-facing edge. The side shield height SH is equal to the distance from the medium facing surface 80 to a point on the pole-facing edge at which the distance between the main pole 15 and the pole-facing edge starts to increase.
The distance from the medium facing surface 80 to an arbitrary point on the second sidewall SW2 may be constant regardless of the distance from the arbitrary point to the top surface 1a of the substrate 1, or may increase or decrease with decreasing distance from the arbitrary point to the top surface 1a of the substrate 1. Similarly, the distance from the medium facing surface 80 to an arbitrary point on the fourth sidewall SW4 may be constant regardless of the distance from the arbitrary point to the top surface 1a of the substrate 1, or may increase or decrease with decreasing distance from the arbitrary point to the top surface 1a of the substrate 1. In all of the above cases, the second sidewall SW2 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the first sidewall SW1, and the fourth sidewall SW4 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the third sidewall SW3. In other words, the second sidewall SW2 and the fourth sidewall SW4 are closer to perpendicular to the top surface 1a of the substrate 1 than are the first sidewall SW1 and the third sidewall SW3.
For the case where the distance from the medium facing surface 80 to an arbitrary point on each of the sidewalls SW2 and SW4 increases with decreasing distance from the arbitrary point to the top surface 1a of the substrate 1, the angle formed by each of the sidewalls SW2 and SW4 with respect to the direction perpendicular to the top surface 1a of the substrate 1 will be expressed in positive values. For the case where the distance from the medium facing surface 80 to an arbitrary point on each of the sidewalls SW2 and SW4 decreases with decreasing distance from the arbitrary point to the top surface 1a of the substrate 1, the angle formed by each of the SW2 and SW4 with respect to the direction perpendicular to the top surface 1a of the substrate 1 will be expressed in negative values. The angle formed by each of the sidewalls SW2 and SW4 with respect to the direction perpendicular to the top surface 1a of the substrate 1 preferably falls within the range of −7° to 7°, more preferably within the range of −7° to 0°. When the foregoing angle is 0°, the sidewalls SW2 and SW4 are perpendicular to the top surface 1a of the substrate 1 and parallel to the medium facing surface 80.
The distance between respective top ends of the sidewalls SW1 and SW3 in the track width direction TW may increase with increasing distance from the medium facing surface 80 as shown in FIG. 2 and FIG. 4, or may be constant regardless of distance from the medium facing surface 80.
As shown in FIG. 1, FIG. 3, FIG. 4 and FIG. 6, the main pole 15 has the end face 15a located in the medium facing surface 80, the top surface 15T farthest from the top surface 1a of the substrate 1, the bottom end 15L opposite to the top surface 15T, and first to sixth side surfaces S1, S2, S3, S4, S5 and S6. As shown in FIG. 3, FIG. 5 and FIG. 7, the end face 15a of the main pole 15 has a first side A1 located at an end of the top surface 15T, and has a second side A2 and a third side A3 opposite to each other in the track width direction TW. The first side A1 is in contact with the second gap layer 19. The distance between the second side A2 and the third side A3 in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1. Each of the second side A2 and the third side A3 forms an angle in the range of, for example, 7° to 17°, or preferably in the range of 10° to 15°, with respect to the direction perpendicular to the top surface 1a of the substrate 1. The first side A1 has a length in the range of 0.05 to 0.20 μm, for example.
As shown in FIG. 1 and FIG. 3, the top surface 15T includes an inclined portion 15T1 and a flat portion 15T2, the inclined portion 15T1 being closer to the medium facing surface 80 than the flat portion 15T2. The inclined portion 15T1 has a first end located in the medium facing surface 80 and a second end opposite thereto. The flat portion 15T2 is connected to the second end of the inclined portion 15T1. The inclined portion 15T1 is inclined such that its second end is located on the front side in the direction T of travel of the recording medium 90 relative to its first end. The flat portion 15T2 extends in a direction substantially perpendicular to the medium facing surface 80. As shown in FIG. 6, the bottom surface of the top shield 16D includes a portion that is opposed to the inclined portion 15T1 with the second gap layer 19 interposed therebetween.
As shown in FIG. 6, the bottom 15L includes an inclined portion and a flat portion, the inclined portion being closer to the medium facing surface 80 than the flat portion. The inclined portion of the bottom end 15L has a first end located in the medium facing surface 80 and a second end opposite thereto. The inclined portion of the bottom end 15L may be an edge formed by two intersecting planes, or may be a plane connecting two planes to each other. The flat portion of the bottom end 15L is a plane connected to the second end of the inclined portion of the bottom end 15L. The inclined portion of the bottom end 15L is inclined such that its second end is located on the rear side in the direction T of travel of the recording medium 90 relative to its first end. The flat portion of the bottom end 15L extends in a direction substantially perpendicular to the medium facing surface 80.
As shown in FIG. 1, FIG. 2 and FIG. 5, the bottom shield 16C includes a first layer 16C1, and a second layer 16C2 lying on the first layer 16C1. The top surface 16Cb of the bottom shield 16C is formed by the top surface of the second layer 16C2. As shown in FIG. 6, the inclined portion of the top surface 16Cb of the bottom shield 16C (the top surface of the second layer 16C2) is opposed to the inclined portion of the bottom end 15L with the first gap layer 18 interposed therebetween.
As shown in FIG. 3, the first side surface S1 is connected to the second side A2. The second side surface S2 is located farther from the medium facing surface 80 than is the first side surface S1. The fifth side surface S5 is connected to the second side surface S2, and is located farther from the medium facing surface 80 than is the second side surface S2.
Further, as shown in FIG. 3, the third side surface S3 is connected to the third side A3. The fourth side surface S4 is located farther from the medium facing surface 80 than is the third side surface S3. The sixth side surface S6 is connected to the fourth side surface S4, and is located farther from the medium facing surface 80 than is the fourth side surface S4.
As shown in FIG. 4, the first side surface S1 is opposed to the first sidewall SW1 of the first side shield 16A. The third side surface S3 is opposed to the third sidewall SW3 of the second side shield 16B. As shown in FIG. 3, in any cross section intersecting the first and third side surfaces S1 and S3 and parallel to the end face 15a constituting part of the medium facing surface 80, the distance between the first side surface S1 and the third side surface S3 in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1. The preferred range of the angle formed by each of the side surfaces S1 and S3 with respect to the direction perpendicular to the top surface 1a of the substrate 1 is the same as that for the case of the sidewalls SW1 and SW3.
As shown in FIG. 3, the main pole 15 further has a first connecting surface SA connecting the first side surface S1 and the second side surface S2, and a second connecting surface SB connecting the third side surface S3 and the fourth side surface S4. Each of the first and second connecting surfaces SA and SB has a width that increases with increasing proximity to the top surface 1a of the substrate 1.
As shown in FIG. 4, a portion of the second side surface S2 is opposed to the second sidewall SW2 of the first side shield 16A. A portion of the fourth side surface S4 is opposed to the fourth sidewall SW4 of the second side shield 16B. Hereinafter, the portion of the second side surface S2 opposed to the second sidewall SW2 of the first side shield 16A will be referred to as the first opposed portion. The portion of the fourth side surface S4 opposed to the fourth sidewall SW4 of the second side shield 16B will be referred to as the second opposed portion.
The second side surface S2 includes the first opposed portion, and a first non-opposed portion located between the first opposed portion and the first connecting surface SA. The fourth side surface S4 includes the second opposed portion, and a second non-opposed portion located between the second opposed portion and the second connecting surface SB. FIG. 3 shows an example in which each of the first and second non-opposed portions is composed of two flat surfaces. Alternatively, each of the first and second non-opposed portions may be formed entirely of a single flat or curved surface, or of a combination of a flat surface and a curved surface.
The second side surface S2 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the first side surface S1, and the fourth side surface S4 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the third side surface S3. In other words, the second side surface S2 and the fourth side surface S4 are closer to perpendicular to the top surface 1a of the substrate 1 than are the first side surface S1 and the third side surface S3. The preferred range of the angle formed by each of the side surfaces S2 and S4 with respect to the direction perpendicular to the top surface 1a of the substrate 1 is the same as that for the case of the sidewalls SW2 and SW4.
The distance from the medium facing surface 80 to an arbitrary point on the first opposed portion may be constant regardless of the distance from the arbitrary point to the top surface 1a of the substrate 1, or may increase or decrease with decreasing distance from the arbitrary point to the top surface 1a of the substrate 1. Similarly, the distance from the medium facing surface 80 to an arbitrary point on the second opposed portion may be constant regardless of the distance from the arbitrary point to the top surface 1a of the substrate 1, or may increase or decrease with decreasing distance from the arbitrary point to the top surface 1a of the substrate 1.
In any cross section intersecting the first and second non-opposed portions and parallel to the end face 15a constituting part of the medium facing surface 80, the distance between the first non-opposed portion and the second non-opposed portion in the track width direction TW may be constant regardless of distance from the top surface 1a of the substrate 1, or may increase or decrease with increasing proximity to the top surface 1a of the substrate 1.
FIG. 1 and FIG. 3 show an example in which the distance from the medium facing surface 80 to the boundary between the inclined portion 15T1 and the flat portion 15T2 of the top surface 15T is equal to the distance from the medium facing surface 80 to each of the respective top ends of the first and second opposed portions of the second and fourth side surfaces S2 and S4. Alternatively, however, the distance from the medium facing surface 80 to the aforementioned boundary may be smaller or greater than the distance from the medium facing surface 80 to each of the aforementioned top ends.
Similarly, FIG. 3 shows an example in which the distance from the medium facing surface 80 to the boundary between the inclined portion and the flat portion of the bottom end 15L is equal to the distance from the medium facing surface 80 to each of the respective bottom ends of the first and second connecting surfaces SA and SB. Alternatively, however, the distance from the medium facing surface 80 to the aforementioned boundary may be smaller or greater than the distance from the medium facing surface 80 to each of the aforementioned bottom ends.
In any cross section intersecting the fifth and sixth side surfaces S5 and S6 and parallel to the end face 15a constituting part of the medium facing surface 80, the distance between the fifth side surface S5 and the sixth side surface S6 in the track width direction TW may be constant regardless of distance from the top surface 1a of the substrate 1, or may increase or decrease with increasing proximity to the top surface 1a of the substrate 1. In all of the above cases, the fifth side surface S5 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the first side surface S1, and the sixth side surface S6 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the third side surface S3.
For the case where the distance between the fifth and sixth side surfaces S5 and S6 in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1 in any cross section intersecting the side surfaces S5 and S6 and parallel to the end face 15a constituting part of the medium facing surface 80, the angle formed by each of the side surfaces S5 and S6 with respect to the direction perpendicular to the top surface 1a of the substrate 1 will be expressed in positive values. For the case where the distance between the fifth and sixth side surfaces S5 and S6 in the track width direction TW increases with increasing proximity to the top surface 1a of the substrate 1 in any cross section intersecting the side surfaces S5 and S6 and parallel to the end face 15a constituting part of the medium facing surface 80, the angle formed by each of the side surfaces S5 and S6 with respect to the direction perpendicular to the top surface 1a of the substrate 1 will be expressed in negative values. The angle formed by each of the side surfaces S5 and S6 with respect to the direction perpendicular to the top surface 1a of the substrate 1 preferably falls within the range of −7° to 7°, more preferably within the range of −7° to 0°. When the foregoing angle is 0°, the distance between the fifth side surface S5 and the sixth side surface S6 in the track width direction TW is constant regardless of distance from the top surface 1a of the substrate 1 in any cross section intersecting the fifth and sixth side surfaces S5 and S6 and parallel to the end face 15a constituting part of the medium facing surface 80.
The distance between respective top ends of the side surfaces S1 and S3 in the track width direction TW may increase with increasing distance from the medium facing surface 80 as shown in FIG. 3 and FIG. 4, or may be constant regardless of distance from the medium facing surface 80.
As shown in FIG. 1 and FIG. 4, the first gap layer 18 is disposed along the first to fourth sidewalls SW1 to SW4. As shown in FIG. 4, the first gap layer 18 includes a first portion 18A interposed between the first sidewall SW1 and the first side surface S1 and between the second sidewall SW2 and the second side surface S2, and a second portion 18B interposed between the third sidewall SW3 and the third side surface S3 and between the fourth sidewall SW4 and the fourth side surface S4. Since the first gap layer 18 is a portion of the gap part 17, the gap part 17 can be said to include the first and second portions 18A and 18B.
As shown in FIG. 4, the nonmagnetic layer 61 is present between the fifth side surface S5 of the main pole 15 and the first side shield 16A, and between the sixth side surface S6 of the main pole 15 and the second side shield 16B. On the other hand, any portion of the nonmagnetic layer 61 is not present between the first sidewall SW1 and the first side surface S1, between the second sidewall SW2 and the second side surface S2, between the third sidewall SW3 and the third side surface S3, and between the fourth sidewall SW4 and the fourth side surface S4. Consequently, the distance between the fifth side surface S5 and the first side shield 16A is greater than the distance between the first side surface S1 and the first sidewall SW1 and the distance between the second side surface S2 and the second sidewall SW2. Likewise, the distance between the sixth side surface S6 and the second side shield 16B is greater than the distance between the third side surface S3 and the third sidewall SW3 and the distance between the fourth side surface S4 and the fourth sidewall SW4. The nonmagnetic layer 61 has the function of magnetically separating the main pole 15 from the side shields 16A and 16B at locations away from the medium facing surface 80.
A manufacturing method for the magnetic head according to the present embodiment will now be described. In the manufacturing method for the magnetic head according to the present embodiment, first, as shown in FIG. 6 and FIG. 7, the insulating layer 2, the first read shield layer 3, and the first read shield gap film 4 are formed in this order on the substrate 1. Next, the MR element 5 and leads (not illustrated) connected to the MR element 5 are formed on the first read shield gap film 4. The MR element 5 and the leads are then covered with the second read shield gap film 6. Then, the second read shield layer 7, the nonmagnetic layer 71, the middle shield layer 72, and the nonmagnetic layer 73 are formed in this order on the second read shield gap film 6.
Next, the magnetic layer 31 is formed on the nonmagnetic layer 73 by frame plating, for example. Then, the insulating layer 51 is formed over the entire top surface of the stack. The insulating layer 51 is then polished by, for example, chemical mechanical polishing (hereinafter referred to as CMP), until the magnetic layer 31 is exposed. Next, the magnetic layers 32 and 33 are formed on the magnetic layer 31 by frame plating, for example. The insulating film 52 is then formed over the entire top surface of the stack. Next, the first portion 10 of the coil is formed by frame plating, for example. The insulating layer 53 is then formed in the space between adjacent turns of the first portion 10. Next, the insulating layer 54 is formed over the entire top surface of the stack. The insulating layer 54 is then polished by, for example, CMP, until the first portion 10, the magnetic layers 32 and 33 and the insulating layer 53 are exposed.
Next, the insulating layer 55 is formed over the entire top surface of the stack. The insulating layer 55 is then selectively etched to form therein a first opening for exposing the top surface of the magnetic layer 32, a second opening for exposing the top surface of the magnetic layer 33, and a third opening for exposing the coil connection 10E (see FIG. 8) of the first portion 10. Then, frame plating, for example, is performed so that the magnetic layer 34 is formed on the magnetic layer 32 at the position of the first opening, the magnetic layer 35 is formed on the magnetic layer 33 at the position of the second opening, and the first connection layer 11 (see FIG. 9) is formed on the coil connection 10E at the position of the third opening. Next, the insulating layer 56 is formed over the entire top surface of the stack. The insulating layer 56 is then polished by, for example, CMP, until the magnetic layers 34 and 35 and the first connection layer 11 are exposed.
Next, frame plating, for example, is performed to form an initial first layer that will later become the first layer 16C1 of the bottom shield 16C, to form the magnetic layer 36 on the magnetic layer 35, and to form the second connection layer 12 (see FIG. 9) on the first connection layer 11. Next, the nonmagnetic layer 57 is formed over the entire top surface of the stack. The nonmagnetic layer 57 is then polished by, for example, CMP, until the initial first layer, the magnetic layer 36 and the second connection layer 12 are exposed. Then, the initial first layer and the nonmagnetic layer 57 are taper-etched in part by, for example, ion beam etching, so as to provide the top surface of the initial first layer with a portion to be opposed to the inclined portion of the bottom end 15L of the main pole 15 to be formed later. The initial first layer thereby becomes the first layer 16C1.
Next, the second layer 16C2 of the bottom shield 16 is formed over the first layer 16C1 and the nonmagnetic layer 57 by sputtering or ion beam deposition, for example. The second layer 16C2 will later serve as a seed layer when plating is performed to form a magnetic layer to become the side shields 16A and 16B on the top surface 16Cb of the bottom shield 16C. The second layer 16C2 except a portion lying on the first layer 16C1 will be removed later by etching. The first layer 16C1 and the etched second layer 16C2 form the bottom shield 16C. In the following description, for the sake of convenience, the stack of the first layer 16C1 and the second layer 16C2 will be referred to as the bottom shield 16C even before the second layer 16C2 is etched.
Reference is now made to FIG. 13 to FIG. 23 to describe a series of steps to be performed after the foregoing step up to the formation of an initial main pole which will later become the main pole 15. FIG. 13 to FIG. 23 each show a stack of layers formed in the process of manufacturing the magnetic head. FIG. 13 and FIG. 18 to FIG. 23 each show the top surface of part of the stack. FIG. 14 to FIG. 17 each show a cross section of the stack taken at the position at which the medium facing surface 80 is to be formed. In FIG. 13 and FIG. 18 to FIG. 23, the symbol “ABS” indicates the position at which the medium facing surface 80 is to be formed.
FIG. 13 shows a step that follows the formation of the second layer 16C2. In this step, a photoresist layer of a positive photoresist is patterned by photolithography to form a first resist layer 81 on a region of the top surface 16Cb of the bottom shield 16C (the top surface of the second layer 16C2) where the side shields 16A and 16B are to be formed later. The first resist layer 81 includes a portion 81a shaped to correspond to the shape of the first side shield 16A to be formed later, and a portion 81b shaped to correspond to the shape of the second side shield 16B to be formed later. More specifically, in this step, first, the photoresist layer of a positive photoresist is formed over the entire top surface of the stack. The photoresist layer is formed such that its top surface is higher in level than the top surfaces of the first and second side shields 16A and 16B to be formed later.
Next, the photoresist layer is selectively exposed to light using a photomask. When exposing the photoresist layer to light, optical proximity correction (hereinafter referred to as OPC) may be employed to form the first resist layer 81 into a shape closer to a desired one. In OPC, the pattern of the photomask is determined so that the photoresist layer to be patterned by photolithography will have a shape closer to a desired one. FIG. 12 is a plan view showing the shape of the photomask in the case of employing OPC in this step. The photomask 100 shown in FIG. 12 has a light-transmitting part 101 which allows the light for exposure to pass therethrough, and a light-blocking part 102 which blocks the light for exposure. The light-blocking part 102 includes a portion 102a shaped to correspond to the planar shape of the first side shield 16A to be formed later, and a portion 102b shaped to correspond to the planar shape of the second side shield 16B to be formed later. In FIG. 13, the portions 102a and 102b are shown by chain double-dashed lines. Next, the exposed photoresist layer is developed. As a result of the exposure, the area of the photoresist layer irradiated with the light having passed through the light-transmitting part 101 of the photomask 100 becomes soluble in a developing solution, while the other area remains insoluble in the developing solution. The photoresist layer remaining after the development makes the first resist layer 81.
The portion 81a of the first resist layer 81 has a wall face 81a1 which includes a portion corresponding to the first sidewall SW1 of the first side shield 16A to be formed later. The portion 81b of the first resist layer 81 has a wall face 81b1 which includes a portion corresponding to the third sidewall SW3 of the second side shield 16B to be formed later. In this step, the photoresist layer is patterned so that both the wall faces 81a1 and 81b1 become inclined relative to the direction perpendicular to the top surface 1a of the substrate 1 and that the distance between the portion of the wall face 81a1 corresponding to the sidewall SW1 and the portion of the wall face 81b1 corresponding to the sidewall SW3 decreases with increasing proximity to the top surface 1a (see FIG. 6) of the substrate 1. Such patterning can be accomplished by using a photoresist layer that consists of a lower layer of low sensitivity and an upper layer of high sensitivity. When viewed from above, in a region other than the location at which the first sidewall SW1 is to be formed, the portion 81a of the first resist layer 81 covers a larger area than the area in which the first side shield 16A is to be formed. When viewed from above, in a region other than the location at which the third sidewall SW3 is to be formed, the portion 81b of the first resist layer 81 covers a larger area than the area in which the second side shield 16B is to be formed.
FIG. 14 shows the next step. In this step, a separating film 82 of a nonmagnetic material is formed to cover the first resist layer 81. The separating film 82 is provided to prevent the first resist layer 81 of a positive photoresist from being mixed with a photoresist layer of a negative photoresist that will be formed later. The separating film 82 has a thickness in the range of 5 to 20 nm, for example. The separating film 82 may be formed of alumina or a synthetic resin, for example. Where alumina is selected as the material for the separating film 82, the separating film 82 is formed by ion beam deposition, for example.
FIG. 15 shows the next step. In this step, a photoresist layer of a negative photoresist is patterned by photolithography to form a second resist layer 83 on the separating film 82. The second resist layer 83 has an opening 83a shaped to correspond to the shape of the first side shield 16A to be formed later, and an opening 83b shaped to correspond to the shape of the second side shield 16B to be formed later. More specifically, in this step, first, the photoresist layer of a negative photoresist is formed over the entire top surface of the stack. The photoresist layer is formed such that its top surface is higher in level than the top surface of a portion of the separating film 82 that lies on the first resist layer 81. Next, the photoresist layer is selectively exposed to light using a photomask. The photomask has a light-transmitting part which allows the light for exposure to pass therethrough, and a light-blocking part which blocks the light for exposure, as does the photomask 100 used when forming the first resist layer 81. The light-blocking part of the photomask includes portions shaped to correspond to the planar shape of the first and second side shields 16A and 16B to be formed later. Next, the exposed photoresist layer is developed. As a result of the exposure, the area of the photoresist layer irradiated with the light having passed through the light-transmitting part of the photomask becomes insoluble in the developing solution, while the other area remains soluble in the developing solution. The photoresist layer remaining after the development makes the second resist layer 83. In this step, OPC may be employed as in the step of forming the first resist layer 81.
FIG. 16 shows the next step. In this step, first, portions of the separating film 82 that are not covered with the second resist layer 83 are removed by wet etching, for example. Next, the first and second resist layers 81 and 83 are exposed to light and then the first resist layer 81 is removed from the openings 83a and 83b of the second resist layer 83. More specifically, first, the entire top surface of the stack is exposed to light. The exposure causes the first resist layer 81 of a positive photoresist to become soluble in a developing solution, and allows the second resist layer 83 of a negative photoresist to remain insoluble in the developing solution. Next, the first resist layer 81 is removed using an alkaline developing solution, for example. In this step, portions of the separating film 82 extending along the wall faces of the openings 83a and 83b of the second resist layer 83 are also removed when or after the first resist layer 81 is removed. In this step, as shown in FIG. 16, a portion of the separating film 82 lying under a narrow portion of the second resist layer 83 may also be removed. Even in such a case, the second resist layer 83 will not peel away since a portion of the separating film 82 lying under a thick portion of the second resist layer 83 remains.
FIG. 17 shows the next step. In this step, after the removal of the first resist layer 81, a first initial side shield 16AP and a second initial side shield 16BP are formed on the top surface 16Cb of the bottom shield 16C (the top surface of the second layer 16C2) by performing plating without forming a seed layer. The second layer 16C2 of the bottom shield 16C is used as a seed layer and an electrode when forming the initial side shields 16AP and 16BP. The initial side shields 16AP and 16BP are formed in the openings 83a and 83b of the second resist layer 83, respectively. The first initial side shield 16AP has the first sidewall SW1 of the first side shield 16A to be formed later, and is larger in planar shape (the shape as viewed from above) than the first side shield 16A. The second initial side shield 16BP has the third sidewall SW3 of the second side shield 16B to be formed later, and is larger in planar shape than the second side shield 16B. Next, as shown in FIG. 18, the second resist layer 83 and the separating film 82 are removed.
FIG. 19 shows the next step. In this step, a mask 84 is formed over the bottom shield 16C and the first and second initial side shields 16AP and 16BP. The mask 84 is formed by patterning a photoresist layer. The mask 84 has a wall face 84a including a portion 84a1 that defines the position of the second sidewall SW2 of the first side shield 16A to be formed later and the position of the fourth sidewall SW4 of the second side shield 16B to be formed later. The mask 84 does not cover a portion of the second layer 16C2 of the bottom shield 16C other than a portion lying on the first layer 16C1.
FIG. 20 shows the next step. In this step, first, using the mask 84 as an etching mask, a portion of the first initial side shield 16AP and a portion of the second initial side shield 16BP are etched by, for example, ion beam etching, so that the first initial side shield 16AP is provided with the second sidewall SW2 and the second initial side shield 16BP is provided with and the fourth sidewall SW4. Further, at the same time the initial side shields 16AP and 16BP are etched, the second layer 16C2 except the portion lying on the first layer 16C1 is removed by etching. This completes the bottom shield 16C composed of the first layer 16C1 and the second layer 16C2 lying thereon. The mask 84 is then removed.
FIG. 21 shows the next step. In this step, the first gap layer 18 is formed over the entire top surface of the stack. Where alumina is selected as the material of the first gap layer 18, the first gap layer 18 is formed by atomic layer deposition (ALD), for example. Where Ru is selected as the material of the first gap layer 18, the first gap layer 18 is formed by chemical vapor deposition (CVD), for example. The first gap layer 18 includes the first and second portions 18A and 18B described previously. Next, the first gap layer 18 is selectively etched to form therein an opening for exposing the top surface of the magnetic layer 36 (see FIG. 6) and an opening for exposing the top surface of the second connection layer 12 (see FIG. 9).
Next, a photoresist layer is formed over the entire top surface of the stack. The photoresist layer is then patterned by photolithography to form a mold 85. The mold 85 is formed such that its top surface is higher in level than the top surfaces of portions of the first gap layer 18 lying on the first and second initial side shields 16AP and 16BP. The mold 85 has an opening 85a for receiving the main pole 15 and an opening for receiving the third connection layer 13 (see FIG. 9). The first initial side shield 16AP, the second initial side shield 16BP, the first gap layer 18 and the mold 85 (the opening 85a) form a receiving portion 86 for receiving the main pole 15.
The opening 85a of the mold 85 has a first inner wall 85a1 defining the shape of the fifth side surface S5 of the main pole 15 and a second inner wall 85a2 defining the shape of the sixth side surface S6 of the main pole 15. When viewed from above, the first inner wall 85a1 intersects a portion of the first gap layer 18 that extends along the second sidewall SW2 of the first initial side shield 16AP. When viewed from above, the second inner wall 85a2 intersects a portion of the first gap layer 18 that extends along the fourth sidewall SW4 of the second initial side shield 16BP. Further, when viewed from above, the first and second inner walls 85a1 and 85a2 are located outwardly from the positions at which the first and third side surfaces S1 and S3 of the main pole 15 are to be formed.
FIG. 22 shows the next step. In this step, an initial main pole 15P which will later become the main pole 15 is formed by plating so as to be received in the receiving portion 86. The initial main pole 15P has the first to sixth side surfaces S1 to S6 and the first and second connecting surfaces SA and SB. As shown in FIG. 22, the shape of the first side surface S1 is defined by the first sidewall SW1 of the first initial side shield 16AP and a portion of the first gap layer 18 that extends along the first sidewall SW1. The shape of the second side surface S2 is defined by the second sidewall SW2 of the first initial side shield 16AP and the portion of the first gap layer 18 that extends along the second sidewall SW2. The shape of the fifth side surface S5 is defined by the first inner wall 85a1 of the mold 85.
Further, as shown in FIG. 22, the shape of the third side surface S3 is defined by the third sidewall SW3 of the second initial side shield 16BP and a portion of the first gap layer 18 that extends along the third sidewall SW3. The shape of the fourth side surface S4 is defined by the fourth sidewall SW4 of the second initial side shield 16BP and the portion of the first gap layer 18 that extends along the fourth sidewall SW4. The shape of the sixth side surface S6 is defined by the second inner wall 85a2 of the mold 85.
Further, the third connection layer 13 (see FIG. 9) is formed on the second connection layer 12 by plating, for example. The initial main pole 15P and the third connection layer 13 are formed such that their top surfaces are higher in level than the top surfaces of the portions of the first gap layer 18 lying on the initial side shields 16AP and 16BP. The mold 85 is then removed.
Reference is now made to FIG. 6 and FIG. 7 to describe steps to follow the formation of the initial main pole 15P and the third connection layer 13. First, the nonmagnetic layer 61 is formed over the entire top surface of the stack. The nonmagnetic layer 61 is then polished until the top surfaces of the first and second initial side shields 16AP and 16BP are exposed. Next, the nonmagnetic metal layer 58 and the insulating layer 59 are formed over the initial main pole 15P and the initial side shields 16AP and 16BP. The initial main pole 15P, the initial side shields 16AP and 16BP and the nonmagnetic layer 61 are then etched in part by, for example, ion beam etching using the nonmagnetic metal layer 58 and the insulating layer 59 so that the initial main pole 15P is provided with the inclined portion 15T1. A portion of the top surface of the etched initial main pole 15P, the portion being covered with the nonmagnetic metal layer 58 and the insulating layer 59, makes the flat portion 15T2.
Next, the second gap layer 19 is formed over the entire top surface of the stack by sputtering or chemical vapor deposition, for example. The second gap layer 19, the nonmagnetic metal layer 58 and the insulating layer 59 are then selectively etched by, for example, ion beam etching, so that a portion of the top surface of the initial main pole 15P, a portion of the top surface of each of the initial side shields 16AP and 16BP, and the top surface of the third connection layer 13 are exposed. Next, the top shield 16D is formed over the initial side shields 16AP and 16BP and the second gap layer 19, and the magnetic layer 41 is formed on the initial main pole 15P by, for example, frame plating.
Next, the insulating film 62 is formed over the entire top surface of the stack. The insulating film 62 is then selectively etched to form therein an opening for exposing the top surface of the third connection layer 13. Next, the first layer 21 of the second portion 20 of the coil is formed by frame plating, for example. Then, the first nonmagnetic layer, not illustrated, is formed over the entire top surface of the stack. The first nonmagnetic layer is then polished by, for example, CMP, until the first layer 21, the top shield 16D and the magnetic layer 41 are exposed.
Next, the insulating layer 63 is formed over the entire top surface of the stack. The insulating layer 63 is then selectively etched to form therein a first opening for exposing the top surface of the top shield 16D and a second opening for exposing the top surface of the magnetic layer 41. Then, frame plating, for example, is performed so that the magnetic layer 42 is formed on the top shield 16D at the position of the first opening and the magnetic layer 43 is formed on the magnetic layer 41 at the position of the second opening.
Next, the insulating film 64 is formed over the entire top surface of the stack. The insulating layer 63 and the insulating film 64 are then selectively etched to form therein openings for exposing the coil connection 21E (see FIG. 10) of the first layer 21. Next, the second layer 22 of the second portion 20 of the coil is formed by frame plating, for example. Then, the second nonmagnetic layer, not illustrated, is formed over the entire top surface of the stack. The second nonmagnetic layer is then polished by, for example, CMP, until the second layer 22 and the magnetic layers 42 and 43 are exposed.
Next, the insulating layer 65 is formed over the entire top surface of the stack. The insulating layer 65 is then selectively etched to form therein an opening for exposing the top surface of the magnetic layer 42 and an opening for exposing the top surface of the magnetic layer 43. Next, the magnetic layer 44 is formed by frame plating, for example. The top shield 16D and the magnetic layers 42 and 44 are then etched by, for example, reactive ion etching or ion beam etching so as to provide the top shield 16D with the connecting surface mentioned previously and provide the magnetic layers 42 and 44 with the respective end faces mentioned previously. Next, the nonmagnetic layer 66 is formed over the entire top surface of the stack. The nonmagnetic layer 66 is then polished by, for example, CMP, until the magnetic layer 44 is exposed.
Next, the protective layer 70 is formed to cover the entire top surface of the stack. Wiring, terminals and other components are then formed on the protective layer 70, and the substrate 1 is cut near the position ABS at which the medium facing surface 80 is to be formed. Next, as shown in FIG. 23, the cut surface is polished to form the medium facing surface 80 so that the first initial side shield 16AP becomes the first side shield 16A, the second initial side shield 16BP becomes the second side shield 16B, and the initial main pole 15P becomes the main pole 15. Then, fabrication of flying rails and other processes are performed to complete the magnetic head.
As has been described, the manufacturing method for the magnetic head according to the present embodiment includes: the step of forming the first initial side shield 16AP having the first sidewall SW1 and the second initial side shield 16BP having the third sidewall SW3 (see FIG. 18); the etching step (see FIG. 20) of etching a portion of the first initial side shield 16AP and a portion of the second initial side shield 16BP so that the first initial side shield 16AP is provided with the second sidewall SW2 and the second initial side shield 16BP is provided with the fourth sidewall SW4; the step of forming the first and second portions 18A and 18B of the gap part 17 (the gap layer 18) (see FIG. 21) after the etching step; the step of forming the initial main pole 15P (see FIG. 22) after the step of forming the first and second portions 18A and 18B of the gap part 17; the step of forming the coil; and the step of forming the medium facing surface 80 (see FIG. 23). The manufacturing method for the magnetic head according to the present embodiment further includes the step of forming the mold 85 (see FIG. 21) having the first and second inner walls 85a1 and 85a2 defining the shapes of the fifth and sixth side surfaces S5 and S6 of the main pole 15, respectively. The step of forming the mold 85 is performed between the step of forming the first and second portions 18A and 18B of the gap part 17 and the step of forming the initial main pole 15P.
The specific functions and effects of the magnetic head according to the present embodiment will now be described. In the present embodiment, the write shield 16 includes the first side shield 16A, the second side shield 16B, the bottom shield 16C and the top shield 16D. The embodiment makes it possible that, in regions on opposite sides of the end face 15a of the main pole 15 in the track width direction TW and regions on the front and rear sides in the direction T of travel of the recording medium 90 relative to the end face 15a of the main pole 15, a magnetic flux that is produced from the end face 15a of the main pole 15 and spreads in directions other than the direction perpendicular to the plane of the recording medium 90 can be captured and thereby prevented from reaching the recording medium 90. The embodiment thereby allows for preventing the occurrence of unwanted erasure.
Further, in the present embodiment, the end face 15a of the main pole 15 located in the medium facing surface 80 has the second and third sides A2 and A3 which are opposite to each other in the track width direction TW, and the distance between the second side A2 and the third side A3 in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1. The embodiment thereby makes it possible to prevent the occurrence of unwanted erasure induced by a skew.
Further, in the present embodiment, the main pole 15 has the first to sixth side surfaces S1 to S6 defined as above, and the write shield 16 includes the first and second side shields 16A and 16B. Now, a magnetic head that has a main pole and first and second side shields formed by the following manufacturing method will be contemplated as a comparative example against the present embodiment. The manufacturing method for the magnetic head of the comparative example is the same as the manufacturing method for the magnetic head according to the present embodiment up to the step shown in FIG. 18. Subsequent to the step of FIG. 18, the manufacturing method for the magnetic head of the comparative example proceeds to the step shown in FIG. 21, that is, the step of forming the first gap layer 18, omitting the step shown in FIG. 19 (the step of forming the mask 84) and the step shown in FIG. 20 (the step of etching the initial side shields 16AP and 16BP). Steps to be performed thereafter are the same as those in the manufacturing method for the magnetic head according to the present embodiment.
FIG. 24 is a plan view showing part of the main pole and the first and second side shields in the vicinity of the medium facing surface in the magnetic head of the comparative example. The magnetic head of the comparative example has the main pole 115, the first side shield 116A and the second side shield 116B that are shaped as shown in FIG. 24. The first side shield 116A has a first end face 16Aa located in the medium facing surface 80, and has a first sidewall SW11 and a second sidewall SW12 facing the main pole 115. The second side shield 116B has a second end face 16Ba located in the medium facing surface 80, and has a third sidewall SW13 and a fourth sidewall SW14 facing the main pole 115. The first sidewall SW11 is connected to the first end face 16Aa. The second sidewall SW12 is connected to the first sidewall SW11, and is located farther from the medium facing surface 80 than is the first sidewall SW11. The third sidewall SW13 is connected to the second end face 16Ba. The fourth sidewall SW14 is connected to the third sidewall SW13, and is located farther from the medium facing surface 80 than is the third sidewall SW13.
The main pole 115 includes: a track width defining portion having an end face located in the medium facing surface 80 and an end opposite to the end face; and a wide portion connected to the end of the track width defining portion. In the track width defining portion, the width of the top surface of the main pole 115 in the track width direction TW gradually increases with increasing distance from the medium facing surface 80. The width of the top surface of the main pole 115 in the track width direction TW is greater in the wide portion than in the track width defining portion.
Further, the main pole 115 has an end face 115a located in the medium facing surface 80, and first to sixth side surfaces S11, S12, S13, S14, S15 and S16. The first side surface S11 is connected to the end face 115a and opposed to the first sidewall SW11 of the first side shield 116A. The second side surface S12 is connected to the first side surface S11 and opposed to the second sidewall SW12 of the first side shield 116A. The third side surface S13 is connected to the end face 115a and opposed to the third sidewall SW13 of the second side shield 116B. The fourth side surface S14 is connected to the third side surface S13 and opposed to the fourth sidewall SW14 of the second side shield 116B. The fifth side surface S15 is connected to the second side surface S12 and located farther from the medium facing surface 80 than is the second side surface S12. The sixth side surface S16 is connected to the fourth side surface S14 and located farther from the medium facing surface 80 than is the fourth side surface S14.
The distance from the medium facing surface 80 to the boundary between the track width defining portion and the wide portion on the top surface of the main pole 115 is equal to the distance from the medium facing surface 80 to the boundary between the second side surface S12 and the fifth side surface S15, and equal to the distance from the medium facing surface 80 to the boundary between the fourth side surface S14 and the sixth side surface S16. Here, the distance from the medium facing surface 80 to the boundary between the track width defining portion and the wide portion on the top surface of the main pole 115, that is, the length of the track width defining portion in the direction perpendicular to the medium facing surface 80, will be defined as the neck height of the comparative example.
In the comparative example, the first and second side shields 116A and 116B are formed in the openings 83a and 83b of the second resist layer 83, respectively, like the initial side shields 16AP and 16BP of the present embodiment. The openings 83a and 83b are defined in shape by photolithography. Accordingly, in the comparative example, the top surfaces of the side shields 116A and 116B are defined in shape by photolithography. In this case, as shown in FIG. 24, portions of edges of the top surfaces of the side shields 116A and 116B in the vicinity of the main pole 115 are each formed into the shape of an arc having a large radius of curvature.
Here, an edge of the top surface of each of the side shields 116A and 116B that faces the main pole 115 will be referred to as the pole-facing edge, and the distance from the medium facing surface 80 to a point on the pole-facing edge at which the distance between the main pole 115 and the pole-facing edge starts to increase will be denoted by symbol H, as shown in FIG. 24. The distance H corresponds to the side shield height SH of the present embodiment. In the comparative example, an attempt to reduce the distance H would lead to an increase in the distance between the side shields 116A and 116B in the medium facing surface 80, thus precluding a reduction of the track width of the main pole 115 to a desired small value. On the other hand, an attempt to reduce the track width of the main pole 115 to a desired small value would lead to an increase in the distance H. Accordingly, in the comparative example, it is not possible to reduce the neck height of the main pole 115 while reducing the track width of the main pole 115 to a desired small value. Further, in the comparative example, the second and fourth sidewalls SW12 and SW14 form the same angles as the first and third sidewalls SW11 and SW13, respectively, with respect to the direction perpendicular to the top surface 1a of the substrate 1. As a result, the second side surface S12 is inclined in the same form as the first side surface S11, and the fourth side surface S14 is inclined in the same form as the third side surface S13. Consequently, in the comparative example, the main pole 115 cannot have a sufficiently large cross-sectional area in the vicinity of the medium facing surface 80.
In the present embodiment, in contrast, it is possible to reduce the side shield height SH shown in FIG. 4 while reducing the track width of the main pole 15 to a desired small value. More specifically, in the present embodiment, the side shield height SH is equal to the distance from the medium facing surface 80 to each of the edges E1 and E2 of the second and fourth sidewalls SW2 and SW4 that are farthest from the top surface 1a of the substrate 1. The position of the edges E1 and E2 is defined by the position of the portion 84a1 of the wall face 84a of the mask 84 shown in FIG. 19. The position of the portion 84a1 can be selected as desired, independently of the track width of the main pole 15, and can be brought close to the position ABS at which the medium facing surface 80 is to be formed.
Here, the distance from the medium facing surface 80 to the boundary between the track width defining portion 15A and the wide portion 15B on the top surface 15T of the main pole 15, that is, the length of the track width defining portion 15A in the direction perpendicular to the medium facing surface 80, will be defined as the neck height of the present embodiment. In the present embodiment, it is possible to reduce the neck height by reducing the side shield height SH.
Further, in the present embodiment, the second sidewall SW2 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the first sidewall SW1, and the fourth sidewall SW4 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the third sidewall SW3. As a result, in the main pole 15 of the present embodiment, the second side surface S2 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the first side surface S1, and the fourth side surface S4 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the third side surface S3.
When compared with the comparative example, the main pole 15 of the present embodiment is larger in cross-sectional area perpendicular to the direction of flow of magnetic flux in the portions near the boundary between the first side surface S1 and the second side surface S2 and the boundary between the third side surface S3 and the fourth side surface S4. Accordingly, when compared with the comparative example, the main pole 15 of the present embodiment allows more magnetic flux to pass through the portion near the boundary between the first side surface S1 and the second side surface S2, that is, near the first connecting surface SA, and the portion near the boundary between the third side surface S3 and the fourth side surface S4, that is, near the second connecting surface SB. Consequently, the present embodiment provides improved write characteristics, such as improved overwrite property, relative to the comparative example.
In the comparative example, the cross-sectional area of the wide portion of the main pole 115 at the boundary between the track width defining portion and the wide portion is limited by the distance between the sidewalls SW12 and SW14. In the present embodiment, in contrast, since the edges E1 and E2 of the second and fourth sidewalls SW2 and SW4 are parallel to the medium facing surface 80, the cross-sectional area of the wide portion 15B of the main pole 15 at the boundary between the track width defining portion 15A and the wide portion 15B can be increased without being limited by the second and fourth sidewalls SW2 and SW4. The embodiment thus allows the main pole 15 to have a larger cross-sectional area in the vicinity of the medium facing surface 80 when compared with the comparative example.
By virtue of the foregoing features, the present embodiment makes it possible to sufficiently increase the cross-sectional area of the main pole 15 in the vicinity of the medium facing surface 80, and consequently allows for further improvement in write characteristics.
The present embodiment is thus able to achieve prevention of unwanted erasure and improvement in write characteristics at the same time.
Second Embodiment
A magnetic head according to a second embodiment of the invention will now be described. FIG. 30 is a cross-sectional view of the magnetic head according to the present embodiment. The arrow labeled T in FIG. 30 indicates the direction of travel of a recording medium. FIG. 31 is a front view showing the medium facing surface of the magnetic head according to the present embodiment. FIG. 32 is a plan view showing a first portion of a coil of the magnetic head according to the present embodiment. FIG. 33 is a plan view showing a second portion of the coil of the magnetic head according to the present embodiment. In each of FIG. 31 to FIG. 33, the arrow labeled TW indicates the track width direction.
The magnetic head according to the present embodiment is configured differently than in the first embodiment in the following ways. The first connection layer 11, the magnetic layers 34, 35, 42 and 43, the insulating layers 53, 56 and 63, the insulating film 64, and the non-illustrated second nonmagnetic layer of the first embodiment are omitted from the magnetic head according to the present embodiment. The bottom shield 16C of the write shield 16 lies on the magnetic layer 32. The magnetic layer 36 lies on the magnetic layer 33. The magnetic layer 44 lies on the top shield 16D of the write shield 16, the magnetic layer 41 and the insulating layer 65, and connects the top shield 16D and the magnetic layer 41 to each other. In the present embodiment, the magnetic layer 32 has an end face located in the medium facing surface 80. The bottom shield 16C is constituted by a single magnetic layer.
In the present embodiment, the coil includes a first portion 110 and a second portion 120, in place of the first portion 10 and the second portion 20 of the first embodiment. The first portion 110 and the second portion 120 are both formed of a conductive material such as copper. The first portion 110 and the second portion 120 are connected in series or in parallel.
As shown in FIG. 32, the first portion 110 of the coil is wound around the magnetic layer 33. In the present embodiment, the insulating film 52 separates the first portion 110 from the magnetic layers 31 to 33. The insulating layer 54 is disposed around the first portion 110 and the magnetic layer 32 and in the space between adjacent turns of the first portion 110. The insulating layer 55 lies on the top surfaces of the first portion 110, the insulating film 52 and the insulating layer 54. The nonmagnetic layer 57 lies on the top surface of the insulating layer 55 and a portion of the top surface of the magnetic layer 32, and surrounds the bottom shield 16C and the magnetic layer 36.
As shown in FIG. 33, the second portion 120 of the coil is wound around the magnetic layer 41. In the present embodiment, the insulating film 62 separates the second portion 120 from the top shield 16D, the second gap layer 19 and the magnetic layer 41. Further, the magnetic head according to the present embodiment includes an insulating layer 67 formed of an insulating material and disposed in the space between adjacent turns of the second portion 120. The insulating layer 65 lies on the top surfaces of the second portion 120, the insulating film 62 and the insulating layer 67. The insulating layer 67 is formed of alumina, for example.
Further, the magnetic head according to the present embodiment includes a main pole 75 in place of the main pole 15 of the first embodiment. The main pole 75 has an end face 75a located in the medium facing surface 80.
In the present embodiment, the first return path section is constituted by the magnetic layers 31 to 33 and 36. As shown in FIG. 30, the first return path section (the magnetic layers 31 to 33 and 36) connects the write shield 16 and part of the main pole 75 located away from the medium facing surface 80 to each other so that a first space is defined by the main pole 75, the gap part 17 (the gap layer 18), the write shield 16 and the first return path section. The first portion 110 of the coil passes through the first space.
In the present embodiment, the second return path section is constituted by the magnetic layers 41 and 44. As shown in FIG. 30, the second return path section (the magnetic layers 41 and 44) connects the write shield 16 and part of the main pole 75 located away from the medium facing surface 80 to each other so that a second space is defined by the main pole 75, the gap part 17 (the gap layer 19), the write shield 16 and the second return path section. The second portion 120 of the coil passes through the second space.
The first and second portions 110 and 120 of the coil will now be described in detail with reference to FIG. 32 and FIG. 33. FIG. 32 is a plan view showing the first portion 110. The first portion 110 is wound approximately twice around the magnetic layer 33. The first portion 110 includes a portion that extends to pass through between the magnetic layer 32 and the magnetic layer 33, in particular, within the first space. The first portion 110 has a coil connection 110E electrically connected to the second portion 120.
FIG. 33 is a plan view showing the second portion 120. The second portion 120 is wound approximately twice around the magnetic layer 41. The second portion 120 includes a portion that extends to pass through between the top shield 16D and the magnetic layer 41, in particular, within the second space. The second portion 120 has a coil connection 120S electrically connected to the coil connection 110E of the first portion 110. The coil connection 120S is electrically connected to the coil connection 110E via the second and third connections layers 12 and 13 shown in FIG. 9 described in the first embodiment section. The second and third connection layers 12 and 13 are stacked in this order on the coil connection 110E. The coil connection 120S lies on the third connection layer 13. In the example shown in FIG. 32 and FIG. 33, the first portion 110 and the second portion 120 are connected in series.
The main pole 75, and the bottom shield 16C, the first side shield 16A, the second side shield 16B and the nonmagnetic layer 57 of the present embodiment will now be described in detail. First, the shape of the main pole 75 will be described with reference to FIG. 25 to FIG. 28. FIG. 25 is an exploded perspective view of the main pole 75, the bottom shield 16C and the side shields 16A and 16B. In FIG. 25, the straight chain double-dashed line labeled L indicates an imaginary straight line perpendicular to the top surface 1a (see FIG. 30 and FIG. 31) of the substrate 1 and passing through the end face 75a of the main pole 75. FIG. 25 depicts the main pole 75, the bottom shield 16C and the side shields 16A and 16B as separate from each other along the imaginary straight line L. FIG. 26 is a perspective view of the main pole 75. FIG. 27 is a cross-sectional view showing the main part of the magnetic head. FIG. 28 is a plan view showing the main pole 75 and the side shields 16A and 16B.
The main pole 75 has: an end face 75a located in the medium facing surface 80; a top surface 75T farthest from the top surface 1a of the substrate 1; a bottom end 75L opposite to the top surface 75T; and first to sixth side surfaces S71, S72, S73, S74, S75 and S76. The end face 75a of the main pole 75 has a first side A71, a second side A72 and a third side A73, the first side A71 being located at an end of the top surface 75T, the second and third sides A72 and A73 being opposite to each other in the track width direction TW. The first side A71 is in contact with the second gap layer 19. The distance between the second side A72 and the third side A73 in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1. The preferred range of the angle formed by each of the second and third sides A72 and A73 with respect to the direction perpendicular to the top surface 1a of the substrate 1 is the same as that for the case of the second and third sides A2 and A3 in the first embodiment. The first side A71 has the same length as that of the first side A1 of the first embodiment, for example.
As shown in FIG. 26, the first side surface S71 is connected to the second side A72. In the present embodiment, in particular, the first side surface S71 is constituted by a plurality of planes. The second side surface S72 is located farther from the medium facing surface 80 than is the first side surface S71. The fifth side surface S75 is connected to the second side surface S72 and located farther from the medium facing surface 80 than is the second side surface S72.
As shown in FIG. 26, the third side surface S73 is connected to the third side A73. In the present embodiment, in particular, the third side surface S73 is constituted by a plurality of planes. The fourth side surface S74 is located farther from the medium facing surface 80 than is the third side surface S73. The sixth side surface S76 is connected to the fourth side surface S74 and located farther from the medium facing surface 80 than is the fourth side surface S74.
As has been described in the first embodiment section, the first side shield 16A has the first end face 16Aa and the first and second sidewalls SW1 and SW2. The second side shield 16B has the second end face 16Ba and the third and fourth sidewalls SW3 and SW4. In the present embodiment, in particular, each of the first sidewall SW1 and the third sidewall SW3 is constituted by a plurality of planes contiguous with each other. As shown in FIG. 28, the first side surface S71 is opposed to the first sidewall SW1. The third side surface S73 is opposed to the third sidewall SW3. As shown in FIG. 26, in any cross section intersecting the first and third side surfaces S71 and S73 and parallel to the end face 75a which is part of the medium facing surface 80, the distance between the first side surface S71 and the third side surface S73 in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1. The preferred range of the angle formed by each of the side surfaces S71 and S73 with respect to the direction perpendicular to the top surface 1a of the substrate 1 is the same as that for the case of the sidewalls SW1 and SW3 described in the first embodiment section.
As shown in FIG. 28, the entirety of the second side surface S72 is opposed to the second sidewall SW2. The entirety of the fourth side surface S74 is opposed to the fourth sidewall SW4. The second side surface S72 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the first side surface S71, and the fourth side surface S74 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the third side surface S73. In other words, the second side surface S72 and the fourth side surface S74 are closer to perpendicular to the top surface 1a of the substrate 1 than are the first side surface S71 and the third side surface S73. The preferred range of the angle formed by each of the side surfaces S72 and S74 with respect to the direction perpendicular to the top surface 1a of the substrate 1 is the same as that for the case of the sidewalls SW2 and SW4 described in the first embodiment section.
The second side surface S72 connects the first side surface S71 and the fifth side surface S75 to each other. The fourth side surface S74 connects the third side surface S73 and the sixth side surface S76 to each other. Like the second and fourth side surfaces S72 and S74, the fifth side surface S75 and the sixth side surface S76 are closer to perpendicular to the top surface 1a of the substrate 1 than are the first side surface S71 and the third side surface S73. In other words, the fifth side surface S75 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the first side surface S71, and the sixth side surface S76 forms a smaller angle with respect to the direction perpendicular to the top surface 1a of the substrate 1 than does the third side surface S73. Further, in any cross section intersecting the fifth and sixth side surfaces S75 and S76 and parallel to the medium facing surface 80, the distance between the fifth side surface S75 and the sixth side surface S76 in the track width direction TW may be constant regardless of distance from the top surface 1a of the substrate 1, or may increase or decrease with increasing proximity to the top surface 1a of the substrate 1.
In the present embodiment, as shown in FIG. 28, the first portion 18A of the first gap layer 18 is interposed between the first sidewall SW1 and the first side surface S71 and between the second sidewall SW2 and the second side surface S72. The second portion 18B of the first gap layer 18 is interposed between the third sidewall SW3 and the third side surface S73 and between the fourth sidewall SW4 and the fourth side surface S74.
As shown in FIG. 25 to FIG. 27, the main pole 75 includes a main body 77, and a lower protrusion 76 protruding from the main body 77 toward the top surface 1a (see FIG. 30 and FIG. 31) of the substrate 1. In FIG. 27 the boundary between the main body 77 and the lower protrusion 76 is indicated in a broken line. As shown in FIG. 27, the lower protrusion 76 is located at a distance from the medium facing surface 80. As shown in FIG. 25, FIG. 26 and FIG. 28, the main body 77 includes a front portion 77A and a rear portion 77B. The front portion 77A is located closer to the medium facing surface 80 than is the lower protrusion 76. The rear portion 77B is located farther from the medium facing surface 80 than is the front portion 77A. In FIG. 25 and FIG. 28 the boundary between the front portion 77A and the rear portion 77B is indicated in a broken line.
As shown in FIG. 25, FIG. 26 and FIG. 28, the front portion 77A includes the end face 75a and the first and third side surface S71 and S73 of the main pole 75. The rear portion 75B includes the second, fourth, fifth and sixth side surfaces S72, S74, S75 and S76. Further, the front portion 77A includes a first portion 77Ab which is a portion of the top surface 75T of the main pole 75. The rear portion 77B includes a second portion 77Bb which is the remainder of the top surface 75T of the main pole 75. The first portion 77Ab includes an inclined portion and a flat portion, the inclined portion being located closer to the medium facing surface 80 than is the flat portion. The inclined portion has a first end located in the medium facing surface 80 and a second end opposite thereto. The flat portion is connected to the second end of the inclined portion. The inclined portion is inclined such that its second end is located on the front side in the direction T (see FIG. 27) of travel of the recording medium 90 relative to its first end. The flat portion extends in a direction substantially perpendicular to the medium facing surface 80. The width of the first portion 77Ab in the track width direction TW may gradually increase with increasing distance from the medium facing surface 80 as shown in FIG. 25 and FIG. 28, or may be substantially constant regardless of distance from the medium facing surface 80.
The second portion 77Bb is contiguous with the flat portion of the first portion 77Ab. The second portion 77Bb extends in a direction substantially perpendicular to the medium facing surface 80. As shown in FIG. 25 and FIG. 28, the width in the track width direction TW of the second portion 77Bb is greater than that of the first portion 77Ab at the boundary with the front portion 77A, and increases with increasing distance from the medium facing surface 80.
The front portion 77A has a bottom end 77Ac located opposite to the first portion 77Ab. The bottom end 77Ac has a first end located in the medium facing surface 80 and a second end opposite thereto. The bottom end 77Ac is inclined such that its second end is located on the rear side in the direction T (see FIG. 27) of travel of the recording medium 90 relative to its first end. In the example shown in FIG. 26, the bottom end 77Ac of the front portion 77A includes an edge portion and a planar portion, the edge portion being located closer to the medium facing surface 80 than is the planar portion. The edge portion is an edge formed by two intersecting planes. The planar portion is a plane connecting two planes to each other. Alternatively, the entirety of the bottom end 77Ac may be constituted by the planar portion.
As shown in FIG. 26 and FIG. 27, the lower protrusion 76 has a bottom surface 76a, a first side portion 76b and a second side portion 76c. The bottom surface 76a faces toward the top surface 1a (see FIG. 30 and FIG. 31) of the substrate 1. The first and second side portions 76b and 76c are opposite to each other in the track width direction TW. As shown in FIG. 26, in any cross section intersecting the rear portion 77B and parallel to the medium facing surface 80, the rear portion 77B has a greater width in the track width direction TW than that of the lower protrusion 76.
The magnetic layer 36 of the first return path section is in contact with the lower protrusion 76. The magnetic layer 36 corresponds to the “connection layer” of the present invention. In the present embodiment, the entirety of the bottom surface 76a of the lower protrusion 76 is inclined with respect to the direction perpendicular to the medium facing surface 80 such that the lower protrusion 76 gradually increases in thickness with increasing proximity to the magnetic layer 36. The maximum thickness of the lower protrusion 76 is smaller than that of the main body 77.
As shown in FIG. 26 and FIG. 27, the bottom surface 76a of the lower protrusion 76 has an end 76a1 closest to the medium facing surface 80. The end 76a1 is connected to the second end of the bottom end 77Ac of the front portion 77A. The end 76a1 of the bottom surface 76a is at a distance of, for example, 30 to 90 nm from the medium facing surface 80. As shown in FIG. 26, the width in the track width direction TW of the bottom surface 76a is equal to that of the bottom end 77Ac of the front portion 77A at the boundary with the front portion 77A, and increases with increasing distance from the medium facing surface 80.
The first and second side portions 76b and 76c of the lower protrusion 76 are inclined in the following manner. In any cross section intersecting the first and second side portions 76b and 76c and parallel to the medium facing surface 80, the distance between the first side portion 76b and the second side portion 76c in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1. Alternatively, in the aforementioned cross section, the distance between the first side portion 76b and the second side portion 76c in the track width direction TW may be constant regardless of distance from the top surface 1a of the substrate 1.
The shapes and locations of the bottom shield 16C, the first side shield 16A, the second side shield 16B and the nonmagnetic layer 57 will now be described with reference to FIG. 25 to FIG. 29. FIG. 29 is a perspective view showing the bottom shield 16C, the first side shield 16A, the second side shield 16B and the nonmagnetic layer 57. In FIG. 29, the hatched portion represents a cross section of the nonmagnetic layer 57 parallel to the medium facing surface 80. As shown in FIG. 25 and FIG. 27, the bottom shield 16C is located on the rear side in the direction T of travel of the recording medium 90 relative to the front portion 77A. The top shield 16D is located on the front side in the direction T of travel of the recording medium 90 relative to the front portion 77A. As shown in FIG. 25 and FIG. 28, the first and second side shields 16A and 16B are located on opposite sides of the front portion 77A in the track width direction TW.
As shown in FIG. 29, the first sidewall SW1 of the first side shield 16A has a first edge Ea closest to the top surface 1a (see FIG. 30 and FIG. 31) of the substrate 1. The third sidewall SW3 of the second side shield 16B has a second edge Eb closest to the top surface 1a of the substrate 1. In the example shown in FIG. 29, each of the first and second edges Ea and Eb is constituted by a plurality of straight lines contiguous with each other. The distance between the first edge Ea and the second edge Eb in the track width direction TW increases with increasing distance from the medium facing surface 80.
As shown in FIG. 25 and FIG. 29, the bottom shield 16C includes a first receiving section R1 for receiving a portion of the lower protrusion 76, the first receiving section R1 being recessed from the top surface 16Cb. As shown in FIG. 27 and FIG. 29, the nonmagnetic layer 57 is located farther from the medium facing surface 80 than is the bottom shield 16C and contiguous with the bottom shield 16C. The nonmagnetic layer 57 has a second receiving section R2 for receiving the remainder of the lower protrusion 76.
As shown in FIG. 25 and FIG. 29, the first receiving section R1 has a bottom surface R1a, a fifth sidewall SW5 and a sixth sidewall SW6. The bottom surface R1a is opposed to the bottom surface 76a of the lower protrusion 76. The fifth sidewall SW5 is opposed to a portion of the first side portion 76b of the lower protrusion 76. The sixth sidewall SW6 is opposed to a portion of the second side portion 76c of the lower protrusion 76. The bottom surface R1a is inclined with respect to the direction perpendicular to the medium facing surface 80 in the following manner. As shown in FIG. 25, FIG. 27 and FIG. 29, the distance from the top surface 1a (see FIG. 30 and FIG. 31) of the substrate 1 to an arbitrary point on the bottom surface R1a decreases with increasing distance from the arbitrary point to the medium facing surface 80.
In the present embodiment, the top surface 16Cb of the bottom shield 16C is inclined with respect to the direction perpendicular to the medium facing surface 80 in the following manner. As shown in FIG. 25, FIG. 27 and FIG. 29, the distance from the top surface 1a of the substrate 1 to an arbitrary point on the top surface 16Cb decreases with increasing distance from the arbitrary point to the medium facing surface 80. The top surface 16Cb forms a smaller angle with respect to the direction perpendicular to the medium facing surface 80 than does the bottom surface R1a. Alternatively, the top surface 16Cb may extend in a direction substantially perpendicular to the medium facing surface 80.
As shown in FIG. 25 and FIG. 29, the fifth sidewall SW5 of the first receiving section R1 has a third edge Ec farthest from the top surface 1a of the substrate 1. The sixth sidewall SW6 of the first receiving section R1 has a fourth edge Ed farthest from the top surface 1a of the substrate 1. The distance between the third edge Ec and the fourth edge Ed in the track width direction TW increases with increasing distance from the medium facing surface 80.
The fifth and sixth sidewalls SW5 and SW6 of the first receiving section R1 are inclined in the following manner. In any cross section intersecting the fifth and sixth sidewalls SW5 and SW6 and parallel to the medium facing surface 80, the distance between the fifth sidewall SW5 and the sixth sidewall SW6 in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1. Alternatively, in the aforementioned cross section, the distance between the fifth sidewall SW5 and the sixth sidewall SW6 in the track width direction TW may be constant regardless of distance from the top surface 1a of the substrate 1.
As shown in FIG. 29, the second receiving section R2 has a bottom surface R2a, a wall face R2b, and a wall face R2c. The bottom surface R2a is opposed to the bottom surface 76a of the lower protrusion 76. The wall face R2b is opposed to another portion of the first side portion 76b of the lower protrusion 76. The wall face R2c is opposed to another portion of the second side portion 76c of the lower protrusion 76. The bottom surface R2a of the second receiving section R2 is contiguous with the bottom surface R1a of the first receiving section R1. The wall face R2b of the second receiving section R2 is contiguous with the fifth sidewall SW5 of the first receiving section R1. The wall face R2c of the second receiving section R2 is contiguous with the sixth sidewall SW6 of the first receiving section R1.
The bottom surface R2a of the second receiving section R2 is inclined with respect to the direction perpendicular to the medium facing surface 80 in the following manner. As shown in FIG. 27 and FIG. 29, the distance from the top surface 1a (see FIG. 30 and FIG. 31) of the substrate 1 to an arbitrary point on the bottom surface R2a decreases with increasing distance from the arbitrary point to the medium facing surface 80. The bottom surface R2a may form a smaller angle with respect to the direction perpendicular to the medium facing surface 80 than does the bottom surface R1a of the first receiving section R1.
The wall faces R2b and R2c of the second receiving section R2 are inclined in the following manner. In any cross section intersecting the wall faces R2b and R2c and parallel to the medium facing surface 80, the distance between the wall face R2b and the wall face R2c in the track width direction TW decreases with increasing proximity to the top surface 1a of the substrate 1. Alternatively, in the aforementioned cross section, the distance between the wall face R2b and the wall face R2c in the track width direction TW may be constant regardless of distance from the top surface 1a of the substrate 1.
Relative locations of the first receiving section R1 and the main pole 75 with respect to the first and second side shields 16A and 16B will now be described with reference to FIG. 29. As shown in FIG. 29, the third edge Ec is contiguous with the first edge Ea, and the fourth edge Ed is contiguous with the second edge Eb. Thus, the first receiving section R1 is aligned with the first and second side shields 16A and 16B. A portion of the lower protrusion 76 of the main pole 75 is received in the first receiving section R1. Thus, the lower protrusion 76 is also aligned with the first and second side shields 16A and 16B.
A manufacturing method for the magnetic head according to the present embodiment will now be described. The manufacturing method for the magnetic head according to the present embodiment is the same as the method according to the first embodiment up to the step of forming the insulating film 52. In the present embodiment, the first portion 110 of the coil is then formed by frame plating, for example. Next, the insulating layer 54 is formed over the entire top surface of the stack. The insulating film 52 and the insulating layer 54 are then polished by, for example, CMP, until the first portion 110 and the magnetic layers 32 and 33 are exposed.
Next, the insulating layer 55 is formed over the entire top surface of the stack. The insulating layer 55 is then selectively etched to form therein a first opening for exposing the top surface of the magnetic layer 32, a second opening for exposing the top surface of the magnetic layer 33, and a third opening for exposing the coil connection 110E (see FIG. 32) of the first portion 110. Then, an initial bottom shield, which will later become the bottom shield 16C, is formed on the magnetic layer 32 at the location of the first opening, the magnetic layer 36 is formed on the magnetic layer 33 at the location of the second opening, and the second connection layer 12 (see FIG. 9) is formed on the coil connection 110E at the location of the third opening, by frame plating, for example. Next, an initial nonmagnetic layer, which will later become the nonmagnetic layer 57, is formed over the entire top surface of the stack. The initial nonmagnetic layer is then polished by, for example, CMP, until the initial bottom shield, the magnetic layer 36 and the second connection layer 12 are exposed. Next, portions of the initial bottom shield and the initial nonmagnetic layer are taper-etched by, for example, ion beam etching, so as to provide the initial bottom shield with the top surface 16Cb. Portions of the magnetic layer 36 and the second connection layer 12 are also etched in this etching process.
Reference is now made to FIG. 34A to FIG. 41B to describe a series of steps to be performed after the foregoing step up to the formation of an initial main pole, which will later become the main pole 75. FIG. 34A to FIG. 41B each show a stack of layers formed in the process of manufacturing the magnetic head. In these figures, the symbol 16CP represents the initial bottom shield, and the symbol 57P represents the initial nonmagnetic layer. Portions that are closer to the substrate 1 relative to the initial bottom shield 16CP and the initial nonmagnetic layer 57P are omitted from these figures. The symbol “ABS” shown in some of these figures indicates the location at which the medium facing surface 80 is to be formed.
Fig. nA (n is an integer between 34 and 41 inclusive) shows the top surface of part of the stack. Fig. nB shows a cross section of the stack taken at the location at which the medium facing surface 80 is to be formed. FIG. 36C, FIG. 37C and FIG. 38C each show a cross section perpendicular to the medium facing surface 80 and to the top surface 1a of the substrate 1. The line 36C-36C on FIG. 36A indicates the location of the cross section shown in FIG. 36C. The line 37C-37C on FIG. 37A indicates the location of the cross section shown in FIG. 37C. The line 38C-38C on FIG. 38A indicates the location of the cross section shown in FIG. 38C. FIG. 36D is a perspective view illustrating the step of FIG. 36A to FIG. 36C. FIG. 37D is a perspective view illustrating the step of FIG. 37A to FIG. 37C. FIG. 38D is a perspective view illustrating the step of FIG. 38A to FIG. 38C.
FIG. 34A and FIG. 34B show a step to follow the taper-etching of the portions of the initial bottom shield 16CP and the initial nonmagnetic layer 57P. In this step, first, a seed layer (not illustrated) is formed over the initial bottom shield 16CP and the initial nonmagnetic layer 57P by sputtering or ion beam deposition, for example. Next, a first resist layer 181 is formed over the initial bottom shield 16CP and the initial nonmagnetic layer 57P. The first resist layer 181 has an opening 181a shaped to correspond to the shape of the main pole 75 to be formed later. The first resist layer 181 also includes portions shaped to correspond to the first and second side shields 16A and 16B to be formed later. Like the first resist layer 81 of the first embodiment, the first resist layer 181 is formed by patterning a photoresist layer of a positive photoresist by photolithography. In the present embodiment, in particular, the light-transmitting part of the photomask used in forming the first resist layer 181 includes a portion shaped to correspond to the planar shape of the main pole 75 to be formed later.
The opening 181a of the first resist layer 181 has a wall face 181a1 including a portion corresponding to the sidewall SW1 of the first side shield 16A to be formed later, and a wall face 181a2 including a portion corresponding to the sidewall SW3 of the second side shield 16B to be formed later. In this step, the first resist layer 181 is formed such that both the wall faces 181a1 and 181a2 become inclined with respect to the direction perpendicular to the top surface 1a (see FIG. 30 and FIG. 31) of the substrate 1 and that the distance between the portion of the wall face 181a1 corresponding to the sidewall SW1 and the portion of the wall face 181a2 corresponding to the sidewall SW3 decreases with increasing proximity to the top surface 1a of the substrate 1.
FIG. 35A and FIG. 35B show the next step. In this step, first, a separating film 182 of a nonmagnetic material is formed to cover the first resist layer 181. The function, thickness, material and formation method of the separating film 182 are the same as those of the separating film 82 of the first embodiment. Next, a second resist layer 183 is formed on the separating film 182. The second resist layer 183 is shaped to correspond to the shape of the main pole 75 to be formed later. Like the second resist layer 83 of the first embodiment, the second resist layer 183 is formed by patterning a photoresist layer of a negative photoresist by photolithography. In the present embodiment, in particular, the light-transmitting part of the photomask used in forming the second resist layer 183 includes a portion shaped to correspond to the planar shape of the main pole 75 to be formed later.
FIG. 36A to FIG. 36D show the next step. In FIG. 36D, the hatched portion represents a cross section of the initial nonmagnetic layer 57P parallel to the medium facing surface 80 to be formed later. FIG. 36C omits the illustration of the separating film 182. FIG. 36D omits the illustration of the separating film 182 and the second resist layer 183. In this step, first, portions of the separating film 182 that are not covered with the second resist layer 183 are removed by wet etching, for example. Next, the first and second resist layers 181 and 183 are exposed to light and then the first resist layer 181 is removed. The removal method for the first resist layer 181 is the same as that for the first resist layer 81 of the first embodiment. In this step, portions of the separating film 182 extending along the wall faces of the second resist layer 183 are also removed when or after the first resist layer 181 is removed. In this step, a portion of the separating film 182 lying under a narrow portion of the second resist layer 183 may also be removed. Even in such a case, the second resist layer 183 will not peel away since a portion of the separating film 182 lying under a thick portion of the second resist layer 183 remains.
Next, a first initial side shield 16AP, which will later become the first side shield 16A, and a second initial side shield 16BP, which will later become the second side shield 16B, are formed over the initial bottom shield 16CP and the initial nonmagnetic layer 57P by performing plating, using the non-illustrated seed layer as an electrode and a seed. The second resist layer 183 and the separating film 182 are then removed.
In the present embodiment, the first initial side shield 16AP includes a first pre-side-shield portion 16AP1 to become the first side shield 16A, and a first portion to be removed 16AP2 which will be removed in an etching step to be described later. In FIG. 36A and FIG. 36D, the boundary between the first pre-side-shield portion 16AP1 and the first portion to be removed 16AP2 is indicated in a dotted line. The first pre-side-shield portion 16AP1 has the first sidewall SW1 of the first side shield 16A to be formed later. The first portion to be removed 16AP2 has a seventh sidewall SW7 contiguous with the first sidewall SW1. The seventh sidewall SW7 has an edge Ee closest to the top surface 1a of the substrate 1. The edge Ee is contiguous with the first edge Ea of the first sidewall SW1.
The second initial side shield 16BP includes a second pre-side-shield portion 16BP1 to become the second side shield 16B, and a second portion to be removed 16BP2 which will be removed in the etching step to be described later. In FIG. 36A and FIG. 36D, the boundary between the second pre-side-shield portion 16BP1 and the second portion to be removed 16BP2 is indicated in a dotted line. The second pre-side-shield portion 16BP1 has the third sidewall SW3 of the second side shield 16B to be formed later. The second portion to be removed 16BP2 has an eighth sidewall SW8 contiguous with the third sidewall SW3. The eighth sidewall SW8 has an edge Ef closest to the top surface 1a of the substrate 1. The edge Ef is contiguous with the second edge Eb of the third sidewall SW3.
The seventh sidewall SW7 and the eighth sidewall SW8 are connected to each other at a location opposite from the third and fourth sidewalls SW3 and SW4. The formation of the first and second initial side shields 16AP and 16BP results in the formation of a recess 200 in a stack including the initial bottom shield 16CP, the initial nonmagnetic layer 57P, the first initial side shield 16AP and the second initial side shield 16BP, the recess 200 being defined by the sidewalls SW1, SW3, SW7 and SW8. The planar shape of recess 200 corresponds to the planar shape of the lower protrusion 76 of the main pole 75. The top surface of the initial bottom shield 16CP and the top surface of the initial nonmagnetic layer 57P constitute the bottom of the recess 200.
FIG. 37A to FIG. 37D show the next step. In FIG. 37D, the hatched potion represents a cross section of the initial nonmagnetic layer 57P parallel to the medium facing surface 80 to be formed later. In this step, first, a planarization layer 184 is formed to cover the stack including the initial bottom shield 16CP, the initial nonmagnetic layer 57P, the first initial side shield 16AP and the second initial side shield 16BP. In the present embodiment, the planarization layer 184 includes a first layer 184A formed of a resin such as a photoresist and a second layer 184B formed of an inorganic material such as alumina and lying on the first layer 184A. The second layer 184B is provided for preventing a mask to be formed on the planarization layer 184 from losing its shape.
The first layer 184A includes a first portion formed in the recess 200 and a second portion formed on the first and second initial side shields 16AP and 16BP. The first portion of the first layer 184A is greater in thickness than the second portion of the first layer 184A, and the top surface of the first layer 184A has a level difference significantly smaller than the depth (the dimension in the direction perpendicular to the top surface 1a of the substrate 1) of the recess 200. The first portion of the first layer 184A has a large thickness in a portion of the recess 200 that is small in width, and has a small thickness in a portion of the recess 200 that is large in width. As a result, the level of the top surface of the first portion of the first layer 184A is high in the vicinity of the location ABS at which the medium facing surface 80 is to be formed, and becomes lower with increasing proximity to the magnetic layer 36. To make such a state more apparent, a resin material having a lower viscosity is preferably used to form the first layer 184A.
Next, a mask 185 is formed on the planarization layer 184. The mask 185 is formed above the first and second pre-side-shield portions 16AP1 and 16BP1 of the first and second initial side shields 16AP and 16BP. The mask 185 has a wall face 185a including a portion that defines the location of the second sidewall SW2 of the first side shield 16A to be formed later and the location of the fourth sidewall SW4 of the second side shield 16B to be formed later. The mask 185 is formed by patterning a photoresist layer by photolithography, for example.
FIG. 38A to FIG. 38D show the next step. In this step, the planarization layer 184, the first and second initial side shields 16AP and 16BP, the initial bottom shield 16CP and the initial nonmagnetic layer 57P are etched by, for example, ion beam etching, using the mask 185. This step will hereinafter be referred to as the etching step. In the etching step, portions of the first and second initial side shields 16AP and 16BP that are not covered with the mask 185 are etched to remove the first and second portions to be removed 16AP2 and 16BP2 of the first and second initial side shields 16AP and 16BP. Portions of the initial bottom shield 16CP and the initial nonmagnetic layer 57P that are not covered with the mask 185 and the first and second initial side shields 16AP and 16BP are also etched at the same time the first and second initial side shields 16AP and 16BP are etched. As a result of the etching step, the first pre-side-shield portion 16AP1 is provided with the second sidewall SW2, and the second pre-side-shield portion 16BP1 is provided with the fourth sidewall SW4. Further, the initial bottom shield 16CP is provided with the first receiving section R1, and the initial nonmagnetic layer 57P is provided with the second receiving section R2. This makes the initial nonmagnetic layer 57P into the nonmagnetic layer 57. In FIG. 38D, the hatched portion represents a cross section of the nonmagnetic layer 57 parallel to the medium facing surface 80 to be formed later.
As mentioned above, the level of the top surface of the first portion of the first layer 184A of the planarization layer 184 is high in the vicinity of the location ABS, and becomes lower with increasing proximity to the magnetic layer 36. Thus, in the etching step, as the etching of the planarization layer 184 proceeds, a portion of the bottom of the recess 200 closer to the magnetic layer 36 becomes exposed earlier before completion of the etching of the first and second initial side shields 16AP and 16BP. As previously mentioned, the bottom of the recess 200 is constituted by the top surface of the initial bottom shield 16CP and the top surface of the initial nonmagnetic layer 57P. In the recess 200, portions of the top surfaces of the initial bottom shield 16CP and the initial nonmagnetic layer 57P closer to the magnetic layer 36 start to be etched earlier in the etching step. As a result, portions of the bottom surface R1a of the first receiving section R1 and the bottom surface R2a of the second receiving section R2 closer to the magnetic layer 36 become lower in level.
In the etching step, the first receiving section R1 is formed in a self-aligned manner so that the third edge Ec of the fifth sidewall SW5 of the first receiving section R1 coincides with the edge Ee of the seventh sidewall SW7 shown in FIG. 37D, and the fourth edge Ed of the sixth sidewall SW6 of the first receiving section R1 coincides with the edge Ef of the eighth sidewall SW8 shown in FIG. 37D. As a result, the first receiving section R1 is formed in precise alignment with the first and second pre-side-shield portions 16AP1 and 16BP1 so that the third edge Ec of the fifth sidewall SW5 is contiguous with the first edge Ea of the first sidewall SW1, and the fourth edge Ed of the sixth sidewall SW6 is contiguous with the second edge Eb of the third sidewall SW3.
Further, in the etching step, the seventh sidewall SW7 serves to form the wall face R2b of the second receiving section R2 to be contiguous with the fifth sidewall SW5 of the first receiving section R1. Likewise, the eighth sidewall SW8 serves to form the wall face R2c of the second receiving section R2 to be contiguous with the sixth sidewall SW6 of the first receiving section R1.
Where the etching step employs ion beam etching to etch the planarization layer 184, the initial side shields 16AP and 16BP, the initial bottom shield 16CP and the initial nonmagnetic layer 57P, ion beams are projected in three directions, i.e., from the left side (the side of the first initial side shield 16AP), the right side (the side of the second initial side shield 16BP) and the bottom side (the side of the mask 185) in FIG. 38A toward the region where to form the first and second receiving sections R1 and R2, with the direction of travel of the ion beams prearranged to be at an angle of 15° to 50° with respect the direction perpendicular to to the top surface 1a of the substrate 1. The ion beams may sweep. In such a case, the sweep angle may be 45°, for example.
Projecting an ion beam from the left side in FIG. 38A lowers the etching rate for portions of the initial bottom shield 16CP and the initial nonmagnetic layer 57P in the vicinity of the first initial side shield 16AP because of the effect of the shadow of the first initial side shield 16AP. Projecting an ion beam from the right side in FIG. 38A lowers the etching rate for portions of the initial bottom shield 16CP and the initial nonmagnetic layer 57P in the vicinity of the second initial side shield 16BP because of the effect of the shadow of the second initial side shield 16BP. Projecting an ion beam from the bottom side in FIG. 38A lowers the etching rate for a portion of the initial bottom shield 16CP in the vicinity of the mask 185 because of the effect of the shadow of the mask 185. As the etching of the first and second portions to be removed 16AP2 and 16BP2 proceeds to make them decrease in thickness, the effects of the shadows of the first and second initial side shields 16AP and 16BP decrease to increase the aforementioned etching rates in the vicinity of the first and second initial side shields 16AP and 16BP. This results in the formation of the first receiving section R1 with the bottom surface R1a and sidewalls SW5 and SW6 inclined as shown in FIG. 38D, and the second receiving section R2 with the wall faces R2b and R2c inclined as shown in FIG. 38D.
Of the non-illustrated seed layer formed over the initial bottom shield 16CP and the initial nonmagnetic layer 57P, a portion not covered with the mask 185 and the first and second initial side shields 16AP and 16BP is also etched in the etching step. The depth (the dimension in the direction perpendicular to the top surface 1a of the substrate 1) of each of the first and second receiving sections R1 and R2 can be controlled not only by the thickness of the planarization layer 184 and the etching conditions but also by the thickness of the non-illustrated seed layer.
FIG. 39A and FIG. 39B show the next step. In this step, the mask 185 and a portion of the planarization layer 184 that remains after the step of FIG. 38A to FIG. 38D are removed. FIG. 40A and FIG. 40B show the next step. In this step, first, the first gap layer 18 is formed over the entire top surface of the stack. The method of forming the first gap layer 18 is the same as that in the first embodiment. The first gap layer 18 includes the first and second portions 18A and 18B described in the first embodiment section. The first gap layer 18 is then selectively etched to form therein an opening for exposing the top surface of the magnetic layer 34 (see FIG. 30) and an opening for exposing the top surface of the second connection layer 12 (see FIG. 9).
FIG. 41A and FIG. 41B show the next step. In this step, first, a photoresist layer is formed over the entire top surface of the stack and then the photoresist layer is patterned to form a mold. The mold is formed such that its top surface is higher in level than the top surface of the main pole 75 to be formed later. The mold has a first opening for receiving the initial main pole 75P and a second opening for receiving the third connection layer 13 (see FIG. 9). The first opening has a first inner wall which defines the shape of the fifth side surface S75 of the rear portion 77B and a second inner wall which defines the shape of the sixth side surface S76 of the rear portion 77B. When viewed from above, the first and second inner walls are located outside the respective locations at which the first and third side surfaces S71 and S73 of the front portion 77A are to be formed.
Next, the initial main pole 75P is formed to be received in the first opening by performing plating using the mold. Portions of the initial main pole 75P that are formed to be received in the first receiving section R1 and the second receiving section R2 will later become the lower protrusion 76 of the main pole 75. A portion of the initial main pole 75P that is formed between the first sidewall SW1 of the first pre-side-shield portion 16AP1 and the third sidewall SW3 of the second pre-side-shield portion 16BP1 will later become the front portion 77A of the main body 77 of the main pole 75. A portion of the initial main pole 75P that lies on the portions to become the lower protrusion 76 and lies off the first and second receiving sections R1 and R2 will later become the rear portion 77B of the main body 77 of the main pole 75.
The initial main pole 75P has the side surfaces S71 and S73 of the front portion 77A, the side surfaces S72, S74, S75 and S76 (see FIG. 26) of the rear portion 77B, and the bottom surface 76a and side portions 76b and 76c (see FIG. 26) of the lower protrusion 76. The shape of the first side surface S71 is defined by the first sidewall SW1 of the first pre-side-shield portion 16AP1 and a portion of the first gap layer 18 extending along the first sidewall SW1. The shape of the third side surface S73 is defined by the third sidewall SW3 of the second pre-side-shield portion 16BP1 and a portion of the first gap layer 18 extending along the third sidewall SW3.
The shape of the second side surface S72 is defined by the second sidewall SW2 of the first pre-side-shield portion 16AP1 shown in FIG. 38D and FIG. 39A and a portion of the first gap layer 18 extending along the second sidewall SW2. The shape of the fourth side surface S74 is defined by the fourth sidewall SW4 of the second pre-side-shield portion 16BP1 shown in FIG. 38D and FIG. 39A and a portion of the first gap layer 18 extending along the fourth sidewall SW4. The shape of the fifth side surface S75 is defined by the first inner wall of the mold. The shape of the sixth side surface S76 is defined by the second inner wall of the mold.
The shape of the bottom surface 76a is defined by the bottom surfaces R1a and R2a of the first and second receiving sections R1 and R2 shown in FIG. 38D and a portion of the first gap layer 18 extending along the bottom surfaces R1a and R2a. The shape of the first side portion 76b is defined by the fifth sidewall SW5 of the first receiving section R1 and the wall face R2b of the second receiving section R2 shown in FIG. 38D and a portion of the first gap layer 18 extending along the fifth sidewall SW5 and the wall face R2b. The shape of the second side portion 76c is defined by the sixth sidewall SW6 of the first receiving section R1 and the wall face R2c of the second receiving section R2 shown in FIG. 38D and a portion of the first gap layer 18 extending along the sixth sidewall SW6 and the wall face R2c. 
The third connection layer 13 is formed on the second connection layer 12 by performing plating using the mold. The initial main pole 75P and the third connection layer 13 are formed such that their top surfaces are higher in level than the top surfaces of portions of the first gap layer 18 lying on the initial side shields 16AP and 16BP. The mold is then removed.
Reference is now made to FIG. 25, FIG. 28, FIG. 30 and FIG. 31 to describe steps to follow the formation of the initial main pole 75P and the third connection layer 13. First, the nonmagnetic layer 61 is formed over the entire top surface of the stack. The initial main pole 75P, the third connection layer 13, the first gap layer 18 and the nonmagnetic layer 61 are then polished until the top surfaces of the first and second initial side shields 16AP and 16BP are exposed. Next, the nonmagnetic metal layer 58 and the insulating layer 59 are formed over the initial main pole 75P and the initial side shields 16AP and 16BP. The initial main pole 75P, the initial side shields 16AP and 16BP, the first gap layer 18 and the nonmagnetic layer 61 are then etched in part by, for example, ion beam etching, using the nonmagnetic metal layer 58 and the insulating layer 59 so that the initial main pole 75P is provided with the inclined portion of the first portion 77Ab of the top surface 75T of the main pole 75. Of the top surface of the etched initial main pole 75P, a portion covered with the nonmagnetic metal layer 58 and the insulating layer 59 will form the flat portion of the first portion 77Ab of the top surface 75T and the second portion 77Bb of the top surface 75T.
Next, the second gap layer 19 is formed over the entire top surface of the stack by sputtering or chemical vapor deposition, for example. The second gap layer 19, the nonmagnetic metal layer 58 and the insulating layer 59 are then selectively etched by, for example, ion beam etching, so that a portion of the top surface of the initial main pole 75P, a portion of the top surface of each of the initial side shields 16AP and 16BP, and the top surface of the third connection layer 13 are exposed. Next, an initial top shield, which will later become the top shield 16D, is formed over the initial side shields 16AP and 16BP and the second gap layer 19, and the magnetic layer 41 is formed on the initial main pole 75P, by frame plating, for example.
Next, the insulating film 62 is formed over the entire top surface of the stack. The insulating film 62 is then selectively etched to form therein an opening for exposing the top surface of the third connection layer 13. Next, the second portion 120 of the coil is formed by frame plating, for example. The insulating layer 67 is then formed in the space between adjacent turns of the second portion 120. Next, a first nonmagnetic layer (not illustrated) is formed over the entire top surface of the stack. The insulating film 62 and the first nonmagnetic layer are then polished by, for example, CMP, until the second portion 120, the initial top shield and the magnetic layer 41 are exposed.
Next, the insulating layer 65 is formed over the entire top surface of the stack. The insulating layer 65 is then selectively etched to form therein an opening for exposing the top surface of the initial top shield and an opening for exposing the top surface of the magnetic layer 41. Next, the magnetic layer 44 is formed by frame plating, for example. The initial top shield and the magnetic layer 44 are then etched by, for example, reactive ion etching or ion beam etching so as to provide the initial top shield with the connecting surface described in the first embodiment section and provide the magnetic layer 44 with the end face described in the first embodiment section. The subsequent steps are the same as those in the first embodiment.
The specific functions and effects of the magnetic head according to the present embodiment will now be described. In the magnetic head according to the present embodiment, as shown in FIG. 29, the first receiving section R1 is precisely aligned with the first and second side shields 16A and 16B so that the third edge Ec of the fifth sidewall SW5 is contiguous with the first edge Ea of the first sidewall SW1 and the fourth edge Ed of the sixth sidewall SW6 is contiguous with the second edge Eb of the third sidewall SW3. Thus, the lower protrusion 76 of the main pole 75 is also precisely aligned with the first and second side shields 16A and 16B.
In the manufacturing method for the magnetic head according to the present embodiment, the first receiving section R1, the second receiving section R2 and the lower protrusion 76 are formed in a self-aligned manner by using the first and second initial side shields 16AP and 16BR This will be described in detail below. In the present embodiment, the portions of the first and second initial side shields 16AP and 16BP that are not covered with the mask 185 and the portions of the initial bottom shield 16CP and the initial nonmagnetic layer 57P that are not covered with the first and second initial side shields 16AP and 16BP and the mask 185 are etched in the etching step so as to remove the first and second portions to be removed 16AP2 and 16BP2 of the first and second initial side shields 16AP and 16BP, and to form the first receiving section R1 and the second receiving section R2 in the initial bottom shield 16CP and the initial nonmagnetic layer 57P, respectively.
As shown in FIG. 37D, the first portion to be removed 16AP2 has the seventh sidewall SW7 contiguous with the first sidewall SW1, and the second portion to be removed 16BP2 has the eighth sidewall SW8 contiguous with the third sidewall SW3. In the etching step, as described previously, the first receiving section R1 is formed such that the third edge Ec of the fifth sidewall SW5 of the first receiving section R1 coincides with the edge Ee of the seventh sidewall SW7 closest to the top surface 1a of the substrate 1 and the fourth edge Ed of the sixth sidewall SW6 of the first receiving section R1 coincides with the edge Ef of the eighth sidewall SW8 closest to the top surface 1a of the substrate 1. As a result, the first receiving section R1 is formed in precise alignment with the first and second side shields 16A and 16B (the first and second pre-side-shield portions 16AP1 and 16BP1) so that the third edge Ec of the fifth sidewall SW5 is contiguous with the first edge Ea of the first sidewall SW1 and the fourth edge Ed of the sixth sidewall SW6 is contiguous with the second edge Eb of the third sidewall SW3. Further, the initial main pole 75P is formed such that portions thereof are received in the first and second receiving sections R1 and R2. As a result, the main pole 75 is also formed in precise alignment with the first and second side shields 16A and 16B.
Now, the effects of the magnetic head according to the present embodiment and its manufacturing method will be described in comparison with a magnetic head of a comparative example and its manufacturing method. First, a description will be given of the magnetic head of the comparative example and its manufacturing method. Like the magnetic head according to the present embodiment, the magnetic head of the comparative example includes a medium facing surface, a main pole, a write shield, a gap part and a nonmagnetic layer, the write shield including a bottom shield, a top shield, a first side shield and a second side shield, the gap part including a first portion and a second portion. In the magnetic head of the comparative example, the main pole includes a lower protrusion, the lower protrusion having a front end face facing toward the medium facing surface. In the magnetic head of the comparative example, however, the bottom shield does not include any receiving section.
In the manufacturing method for the magnetic head of the comparative example, the main pole is formed in the following manner. First, as in the manufacturing method for the magnetic head according to the present embodiment, parts of the magnetic head are formed on a substrate up to the initial bottom shield and the initial nonmagnetic layer. Then, a mask having an opening shaped to correspond to the planar shape of the lower protrusion of the main pole is formed over the initial bottom shield and the initial nonmagnetic layer. The mask is formed by patterning a photoresist layer by photolithography. Using the mask, the initial nonmagnetic layer is then etched to form therein a recess for receiving the entire lower protrusion of the main pole. The mask is then removed.
Next, first and second initial side shields, which will later become the first and second side shields, respectively, of the comparative example are formed on the top surface of the initial bottom shield. The first initial side shield of the comparative example corresponds to the first initial side shield 16AP of the present embodiment without the first portion to be removed 16AP2. The second initial side shield of the comparative example corresponds to the second initial side shield 16BP of the present embodiment without the second portion to be removed 16BP2.
Next, the first and second portions of the gap part are formed as in the step shown in FIG. 40A and FIG. 40B. Next, an initial main pole is formed by frame plating as in the step shown in FIG. 41A and FIG. 41B. In the manufacturing method for the magnetic head of the comparative example, a portion of the initial main pole that is formed to be received in the recess of the nonmagnetic layer makes the lower protrusion. The subsequent steps are the same as those of the manufacturing method for the magnetic head according to the present embodiment.
In the manufacturing method for the magnetic head of the comparative example, alignment between the lower protrusion and the first and second side shields depends on the position accuracy of the mask formed by photolithography. This manufacturing method suffers misalignment between the lower protrusion and the first and second side shields. If the structure of the magnetic head of the comparative example to be manufactured by this manufacturing method is such that the front end face of the lower protrusion is located near the medium facing surface, the occurrence of the aforementioned misalignment would bring the lower protrusion closer to one of the side shields, which would result in leakage of magnetic flux from the lower protrusion to the one of the side shields. Thus, it is difficult with the magnetic head of the comparative example to achieve both of the following two goals at the same time, the two goals being important for improvement of recording density. A first goal is to provide a main pole that is shaped to be small in the end face located in the medium facing surface and large in the area of a cross section (hereinafter referred to as cross-sectional area) parallel to the medium facing surface in the vicinity of the medium facing surface. A second goal is to reduce leakage of magnetic flux from the main pole to the write shield.
In contrast, according to the present embodiment, since the first receiving section R1 is formed in precise alignment with the first and second side shields 16A and 16B, the lower protrusion 76 of the main pole 75 is also formed in precise alignment with the first and second side shields 16A and 16B, as mentioned previously. The present embodiment thus makes it possible to bring the end 76a1, which is the end of the bottom surface 76a of the lower protrusion 76 closest to the medium facing surface 80, into close proximity to the medium facing surface 80 while preventing leakage of magnetic flux from the lower protrusion 76 to one of the side shields that results from misalignment of the lower protrusion 76. The present embodiment is thus able to achieve both of the aforementioned two goals at the same time. Consequently, according to the present embodiment, it is possible to achieve improved overwrite property, reduced error rate and higher recording density.
Bringing the end 76a1 of the bottom surface 76a of the lower protrusion 76 into close proximity to the medium facing surface 80 allows for reducing leakage of magnetic flux from the main pole 75 to the outside of the main pole 75 and thereby improving overwrite property. For the magnetic head of the comparative example, however, any attempts to bring the front end face of the lower protrusion into close proximity to the medium facing surface should result in reduction in the volume of the bottom shield, thereby causing the bottom shield to be prone to flux saturation. In such a case, there arises the problem of flux leakage from the bottom shield to the recording medium, which gives rise to unwanted erasure.
In the present embodiment, in contrast, the first receiving section R1 is formed in the bottom shield 16C and a portion of the lower protrusion 76 is received in the first receiving section R1. This makes it possible to provide the bottom shield 16C with a sufficient volume to prevent flux saturation, while bringing the end 76a1 of the bottom surface 76a of the lower protrusion 76 into close proximity to the medium facing surface 80. The present embodiment is thus able to reduce flux leakage from the main pole 75 to the outside of the main pole 75 and also from the bottom shield 16C toward the recording medium 90. According to the present embodiment, this also contributes to improved overwrite property, reduced error rate, and higher recording density.
Further, in the manufacturing method for the magnetic head according to the present embodiment, the planarization layer 184 is formed before the etching step, and then the planarization layer 184, the first initial side shield 16AP, the second initial side shield 16BP and the initial nonmagnetic layer 57P are etched in the etching step by using the mask 185. This results in the formation of the first and second receiving sections R1 and R2 having the bottom surfaces R1a and R2a which are inclined in the manner described previously. The initial main pole 75P is formed such that portions thereof are received in the first and second receiving sections R1 and R2. As a result, the entirety of the bottom surface 76a of the lower protrusion 76 is inclined with respect to the direction perpendicular to the medium facing surface 80 such that the lower protrusion 76 gradually increases in thickness with increasing proximity to the magnetic layer 36. In other words, the lower protrusion 76 gradually decreases in thickness with increasing proximity to the front portion 77A of the main body 77. The maximum thickness of the lower protrusion 76 is smaller than that of the main body 77. These features of the present embodiment make it possible to prevent the occurrence of flux saturation at or in the vicinity of the end 76a1 of the bottom surface 76a of the lower protrusion 76.
The other effects of the present embodiment will now be described. In the present embodiment, the distance between the third edge Ec and the fourth edge Ed in the track width direction TW increases with increasing distance from the medium facing surface 80. When compared with a case where the distance between the third edge Ec and the fourth edge Ed in the track width direction TW is constant regardless of distance from the medium facing surface 80, the present embodiment allows the first receiving section R1 to have a greater cross-sectional area at a location away from the first and second side shields 16A and 16B, and accordingly allows the lower protrusion 76 to have a greater cross-sectional area in the vicinity of the medium facing surface 80. According to the present embodiment, this also contributes to improvement in overwrite property.
Further, in the present embodiment, the side shield height SH shown in FIG. 28 is equal to the distance from the medium facing surface 80 to each of the edges E1 and E2 of the second and fourth sidewalls SW2 and SW4, the edges E1 and E2 being farthest from the top surface 1a of the substrate 1. The location of the edges E1 and E2 is defined by the location of the wall face 185a of the mask 185 shown in FIG. 37A to FIG. 38D. In the present embodiment, it is easy to bring the location of the wall face 185a into close proximity to the location ABS at which the medium facing surface 80 is to be formed.
The distance from the medium facing surface 80 to the boundary between the front portion 77A and the rear portion 77B on the top surface of the main pole 75, that is, the length of the front portion 77A in the direction perpendicular to the medium facing surface 80, will be defined as the neck height in the present embodiment. According to the present embodiment, it is possible to reduce the neck height by reducing the side shield height SH.
If the edges E1 and E2 of the second and fourth sidewalls SW2 and SW4 are inclined with respect to the medium facing surface 80, the cross-sectional area of the rear portion 77B at the boundary between the front portion 77A and the rear portion 77B is limited by the second and fourth sidewalls SW2 and SW4. In the present embodiment, in contrast, since the edges E1 and E2 of the second and fourth sidewalls SW2 and SW4 are parallel to the medium facing surface 80, the cross-sectional area of the rear portion 77B at the boundary between the front portion 77A and the rear portion 77B can be increased without being limited by the second and fourth sidewalls SW2 and SW4.
Further, in the present embodiment, in any cross section intersecting the rear portion 77B and parallel to the medium facing surface 80, the rear portion 77B has a greater width in the track width direction TW than that of the lower protrusion 76. The present embodiment allows the rear portion 77B to have a greater cross-sectional area in the vicinity of the medium facing surface 80 when compared with the case where the rear portion 77B has the same width in the track width direction TW as the lower protrusion 76 in the aforementioned cross section. According to the present embodiment, this also contributes to improvement in overwrite property.
The manufacturing method for the magnetic head according to the present embodiment can be applied to the case of forming a main pole 75 that does not include the lower protrusion 76. Such a case will hereinafter be referred to as the modification example. For the modification example, in the step of FIG. 37A to FIG. 37D the first layer 184A of the planarization layer 184 is formed such that the first portion of the first layer 184A formed in the recess 200 has a thickness greater than the depth of the recess 200.
Further, in the etching step of FIG. 38A to FIG. 38D for the modification example, the planarization layer 184 and the first and second initial side shields 16AP and 16BP are etched using the mask 185 by ion beam etching, for example. The ion beam etching in this case is performed with ion beams allowed to travel in a direction at an angle of 45° to 55° with respect to the direction perpendicular to the top surface 1a of the substrate 1. Alternatively, the ion beam etching may be a combination of an etching process in which ion beams travel in a direction at an angle of 0° to 5° with respect to the direction perpendicular to the top surface 1a of the substrate 1 and an etching process in which ion beams travel in a direction at an angle of 45° to 55° with respect to the direction perpendicular to the top surface 1a of the substrate 1.
According to the modification example, the initial bottom shield 16CP and the initial nonmagnetic layer 57P are not etched at all or are hardly etched in the etching step. Thus, an initial main pole 75P that does not include a portion to become the lower protrusion 76 is formed in the step of FIG. 41A and FIG. 41B. This results in the formation of a main pole 75 that does not include the lower protrusion 76.
According to the modification example, since the mask 185 is formed on the planarization layer 184, it is possible to achieve higher precision in forming the mask 185 when compared with the case of forming the mask 185 without forming the planarization layer 184. As a result, it is possible to form the sidewalls SW2 and SW4 of the side shields 16A and 16B with high precision to provide a small side shield height SH with high precision.
The remainder of configuration, function and effects of the present embodiment are similar to those of the first embodiment.
The present invention is not limited to the foregoing embodiments, and various modifications may be made thereto. For example, as far as the requirements of the appended claims are met, the main pole 15 or 75, the first side shield 16A and the second side shield 16B may be shaped and located as desired, and need not necessarily be as in the respective examples illustrated in the foregoing embodiments.
Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. Thus, it is to be understood that, within the scope of the appended claims and equivalents thereof, the invention may be practiced in other than the foregoing most preferable embodiments.

## Claims

1. A magnetic head for perpendicular magnetic recording, comprising:
a medium facing surface configured to face a recording medium;
a coil configured to produce a magnetic field corresponding to data to be written on the recording medium;
a main pole configured to allow a magnetic flux corresponding to the magnetic field produced by the coil to pass, and configured to produce a write magnetic field for writing the data on the recording medium by means of a perpendicular magnetic recording system;
a write shield formed of a magnetic material;
a gap part formed of a nonmagnetic material and provided between the main pole and the write shield;
a return path section;
a nonmagnetic layer; and
a substrate having a top surface, wherein
the coil, the main pole, the write shield, the gap part, the return path section and the nonmagnetic layer are disposed above the top surface of the substrate,
the write shield includes a bottom shield, a top shield, a first side shield and a second side shield, the first side shield and the second side shield being located on opposite sides of the main pole in a track width direction,
the bottom shield has an end face that is located in the medium facing surface at a position on a rear side in a direction of travel of the recording medium relative to an end face of the main pole,
the top shield has an end face that is located in the medium facing surface at a position on a front side in the direction of travel of the recording medium relative to the end face of the main pole,
the first side shield has a first end face located in the medium facing surface, and has a first sidewall and a second sidewall facing the main pole,
the second side shield has a second end face located in the medium facing surface, and has a third sidewall and a fourth sidewall facing the main pole,
the first sidewall is connected to the first end face,
the second sidewall is located farther from the medium facing surface than is the first sidewall,
the third sidewall is connected to the second end face,
the fourth sidewall is located farther from the medium facing surface than is the third sidewall,
in any cross section intersecting the first and third sidewalls and parallel to the medium facing surface, a distance between the first sidewall and the third sidewall in the track width direction decreases with increasing proximity to the top surface of the substrate,
each of the second and fourth sidewalls has an edge farthest from the top surface of the substrate,
the edge of each of the second and fourth sidewalls is parallel to the medium facing surface and located at a distance of 20 to 120 nm from the medium facing surface,
the main pole has the end face located in the medium facing surface, a top surface farthest from the top surface of the substrate, a bottom end opposite to the top surface of the main pole, and a first, a second, a third and a fourth side surface,
the end face of the main pole has a first side located at an end of the top surface of the main pole, and has a second side and a third side opposite to each other in the track width direction,
a distance between the second side and the third side in the track width direction decreases with increasing proximity to the top surface of the substrate,
the first side surface is connected to the second side,
the second side surface is located farther from the medium facing surface than is the first side surface,
the third side surface is connected to the third side,
the fourth side surface is located farther from the medium facing surface than is the third side surface,
the first side surface is opposed to the first sidewall,
a portion of the second side surface is opposed to the second sidewall,
the third side surface is opposed to the third sidewall,
a portion of the fourth side surface is opposed to the fourth sidewall,
in any cross section intersecting the first and third side surfaces and parallel to the medium facing surface, a distance between the first side surface and the third side surface in the track width direction decreases with increasing proximity to the top surface of the substrate,
the gap part includes a first portion interposed between the first sidewall and the first side surface and between the second sidewall and the second side surface, and a second portion interposed between the third sidewall and the third side surface and between the fourth sidewall and the fourth side surface,
the main pole includes a main body, and a lower protrusion protruding from the main body toward the top surface of the substrate,
the lower protrusion is located at a distance from the medium facing surface,
the main body includes a front portion and a rear portion, the front portion being located closer to the medium facing surface than is the lower protrusion, the rear portion being located farther from the medium facing surface than is the front portion,
the front portion includes the end face of the main pole and the first and third side surfaces of the main pole,
the rear portion includes the second and fourth side surfaces,
the lower protrusion has a bottom surface, a first side portion and a second side portion, the bottom surface facing toward the top surface of the substrate, the first and second side portions being opposite to each other in the track width direction,
the return path section is formed of a magnetic material, located on the rear side in the direction of travel of the recording medium relative to the main pole, and connects the lower protrusion and the bottom shield to each other so that a space is defined by the main pole, the gap part, the bottom shield and the return path section,
the return path section includes a connection layer in contact with the lower protrusion,
the nonmagnetic layer is formed of a nonmagnetic material and disposed around the bottom shield and the connection layer,
the bottom shield includes a first receiving section for receiving a portion of the lower protrusion,
the nonmagnetic layer includes a second receiving section for receiving the remainder of the lower protrusion,
the first receiving section has a bottom surface, a fifth sidewall and a sixth sidewall, the fifth sidewall being opposed to a portion of the first side portion, the sixth sidewall being opposed to a portion of the second side portion,
the first sidewall has a first edge closest to the top surface of the substrate,
the second sidewall has a second edge closest to the top surface of the substrate,
the fifth sidewall has a third edge farthest from the top surface of the substrate,
the sixth sidewall has a fourth edge farthest from the top surface of the substrate,
the third edge is contiguous with the first edge,
the fourth edge is contiguous with the second edge, and
an entirety of the bottom surface of the lower protrusion is inclined with respect to a direction perpendicular to the medium facing surface such that the lower protrusion gradually increases in thickness with increasing proximity to the connection layer.

2. The magnetic head for perpendicular magnetic recording according to claim 1, wherein the lower protrusion is smaller in maximum thickness than the main body.

3. The magnetic head for perpendicular magnetic recording according to claim 1, wherein a distance between the third edge and the fourth edge in the track width direction increases with increasing distance from the medium facing surface.

4. The magnetic head for perpendicular magnetic recording according to claim 1, wherein, in any cross section intersecting the rear portion and parallel to the medium facing surface, the rear portion has a greater width in the track width direction than that of the lower protrusion.

5. A manufacturing method for the magnetic head for perpendicular magnetic recording of claim 1, comprising:
a step of forming an initial bottom shield and an initial nonmagnetic layer;
a step of forming a first initial side shield and a second initial side shield after the step of forming the initial bottom shield and the initial nonmagnetic layer, the first initial side shield having the first sidewall, the second initial side shield having the third sidewall;
a step of forming a planarization layer to cover a stack including the initial bottom shield, the initial nonmagnetic layer and the first and second initial side shields;
a step of forming a mask on the planarization layer;
an etching step of etching the planarization layer, the first and second initial side shields, the initial bottom shield and the initial nonmagnetic layer by using the mask so that the first initial side shield is provided with the second sidewall, the second initial side shield is provided with the fourth sidewall, and the first and second receiving sections are formed;
a step of forming the first and second portions of the gap part after the etching step;
a step of forming an initial main pole after the step of forming the first and second portions of the gap part;
a step of forming the coil; and
a step of forming the medium facing surface so that the first initial side shield becomes the first side shield, the second initial side shield becomes the second side shield, and the initial main pole becomes the main pole.

6. The manufacturing method according to claim 5, wherein the planarization layer includes a first layer formed of a resin and a second layer formed of an inorganic material and lying on the first layer.

7. A manufacturing method for a magnetic head for perpendicular magnetic recording, the magnetic head comprising:
a medium facing surface configured to face a recording medium;
a coil configured to produce a magnetic field corresponding to data to be written on the recording medium;
a main pole configured to allow a magnetic flux corresponding to the magnetic field produced by the coil to pass, and configured to produce a write magnetic field for writing the data on the recording medium by means of a perpendicular magnetic recording system;
a write shield formed of a magnetic material;
a gap part formed of a nonmagnetic material and provided between the main pole and the write shield; and
a substrate having a top surface, wherein
the coil, the main pole, the write shield and the gap part are disposed above the top surface of the substrate,
the write shield includes a first side shield and a second side shield located on opposite sides of the main pole in a track width direction,
the first side shield has a first end face located in the medium facing surface, and has a first sidewall and a second sidewall facing the main pole,
the second side shield has a second end face located in the medium facing surface, and has a third sidewall and a fourth sidewall facing the main pole,
the first sidewall is connected to the first end face,
the second sidewall is located farther from the medium facing surface than is the first sidewall,
the third sidewall is connected to the second end face,
the fourth sidewall is located farther from the medium facing surface than is the third sidewall,
in any cross section intersecting the first and third sidewalls and parallel to the medium facing surface, a distance between the first sidewall and the third sidewall in the track width direction decreases with increasing proximity to the top surface of the substrate,
each of the second and fourth sidewalls has an edge farthest from the top surface of the substrate,
the edge of each of the second and fourth sidewalls is parallel to the medium facing surface and located at a distance of 20 to 120 nm from the medium facing surface,
the main pole has an end face located in the medium facing surface, a top surface farthest from the top surface of the substrate, a bottom end opposite to the top surface of the main pole, and a first, a second, a third and a fourth side surface,
the end face of the main pole has a first side located at an end of the top surface of the main pole, and has a second side and a third side opposite to each other in the track width direction,
a distance between the second side and the third side in the track width direction decreases with increasing proximity to the top surface of the substrate,
the first side surface is connected to the second side,
the second side surface is located farther from the medium facing surface than is the first side surface,
the third side surface is connected to the third side,
the fourth side surface is located farther from the medium facing surface than is the third side surface,
the first side surface is opposed to the first sidewall,
a portion of the second side surface is opposed to the second sidewall,
the third side surface is opposed to the third sidewall,
a portion of the fourth side surface is opposed to the fourth sidewall,
in any cross section intersecting the first and third side surfaces and parallel to the medium facing surface, a distance between the first side surface and the third side surface in the track width direction decreases with increasing proximity to the top surface of the substrate, and
the gap part includes a first portion interposed between the first sidewall and the first side surface and between the second sidewall and the second side surface, and a second portion interposed between the third sidewall and the third side surface and between the fourth sidewall and the fourth side surface,
the manufacturing method comprising:
a step of forming a first initial side shield having the first sidewall, and a second initial side shield having the third sidewall;
a step of forming a planarization layer to cover a stack including the first and second initial side shields;
a step of forming a mask on the planarization layer;
an etching step of etching the planarization layer and the first and second initial side shields by using the mask so that the first initial side shield is provided with the second sidewall and the second initial side shield is provided with the fourth sidewall;
a step of forming the first and second portions of the gap part after the etching step;
a step of forming an initial main pole after the step of forming the first and second portions of the gap part;
a step of forming the coil; and
a step of forming the medium facing surface so that the first initial side shield becomes the first side shield, the second initial side shield becomes the second side shield, and the initial main pole becomes the main pole.

8. The manufacturing method according to claim 7, wherein the planarization layer includes a first layer formed of a resin and a second layer formed of an inorganic material and lying on the first layer.