Magnetic write head having a stacked coil architecture for high data rate performance

Approaches for a magnetic write head having a stacked coil architecture. Embodiments utilize the better process control capability available with thin films' thicknesses, compared to the control capability of vertical gap-filling processes, which provides for better scalability to shorter yoke length magnetic write heads, which are faster at writing data bits than are magnetic write heads having a longer yoke length.

FIELD OF THE INVENTION

Embodiments of the invention relate generally to perpendicular magnetic recording and more particularly to a write pole having a stacked coil architecture for high data rate performance.

BACKGROUND

A hard-disk drive (HDD) is a non-volatile storage device that is housed in a protective enclosure and stores digitally encoded data on one or more circular disks having magnetic surfaces (a disk may also be referred to as a platter). When an HDD is in operation, each magnetic-recording disk is rapidly rotated by a spindle system. Data is read from and written to a magnetic-recording disk using a read/write head which is positioned over a specific location of a disk by an actuator.

A read/write head uses a magnetic field to read data from and write data to the surface of a magnetic-recording disk. As a magnetic dipole field decreases rapidly with distance from a magnetic pole, the distance between a read/write head, which is housed in a slider, and the surface of a magnetic-recording disk must be tightly controlled. An actuator relies in part on a suspension's force on the slider and on the aerodynamic characteristics of the slider air bearing surface (ABS) to provide the proper distance between the read/write head and the surface of the magnetic-recording disk (the “flying height”) while the magnetic-recording disk rotates. A slider therefore is said to “fly” over the surface of the magnetic-recording disk.

FIG. 2is a cross-sectional side view of a conventional write head. Write heads make use of the electricity flowing through a coil202in the write head200, which produces a magnetic field. One type of coil design is referred to as a helical coil because it wraps around the write poles, i.e., main pole204, in a helical shape. Such a write head includes a helical write coil having upper coil portions202a,202b,202cthat pass above the write pole and lower coil portions202d,202e,202fthat pass below the write pole. The upper and lower coil portions are connected with one another by connection studs. Electrical pulses are sent to the write head, with different patterns of positive and negative currents. The current in the coil of the write head induces a magnetic field across the gap between the head and the magnetic disk, which in turn magnetizes a small area on the recording medium.

A perpendicular magnetic recording (PMR) system records data as magnetizations oriented perpendicular to the plane of the magnetic-recording disk. The magnetic disk has a magnetically soft underlayer covered by a thin magnetically hard recording layer. The perpendicular write head has a write pole (main pole204) with a very small cross section at the pole tip208a, tapered down from the cross section along the length of the yoke208b, a lower return pole206, and an upper return pole218having a much larger cross section along the length. Also shown inFIG. 2is a wrap-around shield209, for assisting in focusing the magnetic field emitting from pole tip208a, and a back gap203. A strong, highly concentrated magnetic field emits from the write pole in a direction perpendicular to the magnetic disk surface, magnetizing the magnetically hard top layer. The resulting magnetic flux then travels through the soft underlayer, returning to the return pole where it is sufficiently spread out and weak that it will not erase the signal recorded by the write pole when it passes back through the magnetically hard top layer on its way back to the return pole.

Advanced PMR writers demand high data rate write heads, especially for advanced server products. For high data rate performance, a shorter yoke length write head is faster in writing data bits, for the same total write current. Thus, the shorter the yoke length, and the higher the total current going through the coil turns, the faster the write head. However, in conventional write heads, yoke length reduction is challenging in part because manufacturing conventional coil structures involves filling in insulating material into the gaps210a,210band210c,210dbetween coil turns202a,202b,202cand202d,202e,202f, respectively. As the yoke length decreases, the height-to-width aspect ratio of such gaps typically increases, making the insulator fill process all the more problematic.

SUMMARY OF EMBODIMENTS OF THE INVENTION

As discussed, magnetic write heads having a shorter yoke length are more efficient and faster at writing data bits than are magnetic write heads having a longer yoke length. Further, for coil turns carrying the same amount of current, coil turns closer to the main pole tip are more effective at driving the pole than coil turns farther back from the pole tip.

Embodiments of the invention are directed towards a magnetic write head having a stacked coil architecture. Embodiments utilize the better process control capability available with thin films' thicknesses, compared to the control capability of vertical gap-filling processes, which provide for better scalability to shorter yoke length magnetic write heads.

Embodiments discussed in the Summary of Embodiments of the Invention section are not meant to suggest, describe, or teach all the embodiments discussed herein. Thus, embodiments of the invention may contain additional or different features than those discussed in this section.

DETAILED DESCRIPTION

Approaches to the configuration and the manufacturing process for a stacked coil magnetic write head, are described. In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention described herein. It will be apparent, however, that the embodiments of the invention described herein may be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring the embodiments of the invention described herein.

Physical Description of Illustrative Embodiments of the Invention

Embodiments of the invention may be used in the context of the manufacturing and use of a magnetic writer for a hard-disk drive (HDD). In accordance with an embodiment of the invention, a plan view of a HDD100is shown inFIG. 1.FIG. 1illustrates the functional arrangement of components of the HDD including a slider110bthat includes a magnetic-reading/recording head110a. Collectively, slider110band head110amay be referred to as a head slider. The HDD100includes at least one head gimbal assembly (HGA)110including the head slider, a lead suspension110cattached to the head slider, and a load beam110dattached to the lead suspension110c. The HDD100also includes at least one magnetic-recording disk120rotatably mounted on a spindle124and a drive motor (not shown) attached to the spindle124for rotating the disk120. The head110aincludes a write element and a read element for respectively writing and reading information stored on the disk120of the HDD100. The disk120or a plurality (not shown) of disks may be affixed to the spindle124with a disk clamp128.

The HDD100further includes an arm132attached to the HGA110, a carriage134, a voice-coil motor (VCM) that includes an armature136including a voice coil140attached to the carriage134; and a stator144including a voice-coil magnet (not shown). The armature136of the VCM is attached to the carriage134and is configured to move the arm132and the HGA110to access portions of the disk120being mounted on a pivot-shaft148with an interposed pivot-bearing assembly152. In the case of an HDD having multiple disks, or platters as disks are sometimes referred to in the art, the carriage134is called an “E-block,” or comb, because the carriage is arranged to carry a ganged array of arms that gives it the appearance of a comb.

With further reference toFIG. 1, in accordance with an embodiment of the present invention, electrical signals, for example, current to the voice coil140of the VCM, write signal to and read signal from the head110a, are provided by a flexible interconnect cable156(“flex cable”). Interconnection between the flex cable156and the head110amay be provided by an arm-electronics (AE) module160, which may have an on-board pre-amplifier for the read signal, as well as other read-channel and write-channel electronic components. The AE160may be attached to the carriage134as shown. The flex cable156is coupled to an electrical-connector block164, which provides electrical communication through electrical feedthroughs (not shown) provided by an HDD housing168. The HDD housing168, also referred to as a casting, depending upon whether the HDD housing is cast, in conjunction with an HDD cover (not shown) provides a sealed, protective enclosure for the information storage components of the HDD100.

With further reference toFIG. 1, in accordance with an embodiment of the present invention, other electronic components (not shown), including a disk controller and servo electronics including a digital-signal processor (DSP), provide electrical signals to the drive motor, the voice coil140of the VCM and the head110aof the HGA110. The electrical signal provided to the drive motor enables the drive motor to spin providing a torque to the spindle124which is in turn transmitted to the disk120that is affixed to the spindle124by the disk clamp128; as a result, the disk120spins in a direction172. The spinning disk120creates a cushion of air that acts as an air-bearing on which the air-bearing surface (ABS) of the slider110brides so that the slider110bflies above the surface of the disk120without making contact with a thin magnetic-recording medium of the disk120in which information is recorded.

The electrical signal provided to the voice coil140of the VCM enables the head110aof the HGA110to access a track176on which information is recorded. Thus, the armature136of the VCM swings through an arc180which enables the HGA110attached to the armature136by the arm132to access various tracks on the disk120. Information is stored on the disk120in a plurality of stacked tracks (not shown) arranged in sectors on the disk120, for example, sector184. Correspondingly, each track is composed of a plurality of sectored track portions, for example, sectored track portion188. Each sectored track portion188is composed of recorded data and a header containing a servo-burst-signal pattern, for example, an ABCD-servo-burst-signal pattern, information that identifies the track176, and error correction code information. In accessing the track176, the read element of the head110aof the HGA110reads the servo-burst-signal pattern which provides a position-error-signal (PES) to the servo electronics, which controls the electrical signal provided to the voice coil140of the VCM, enabling the head110ato follow the track176. Upon finding the track176and identifying a particular sectored track portion188, the head110aeither reads data from the track176or writes data to the track176depending on instructions received by the disk controller from an external agent, for example, a microprocessor of a computer system.

Magnetic Write Head Stacked Coil Architecture

As mentioned, a shorter yoke-length write head is faster in writing data bits for the same total write current. Thus, the shorter the yoke length, the faster the write head. However, in conventional write heads, yoke length reduction is challenging in part because manufacturing conventional coil structures involves filling in insulating material in between coil turns and between the coil and upper return pole and as the yoke length decreases, the height-to-width aspect ratio of such insulating material typically increases, making the insulator fill process all the more problematic. Furthermore, coil turns closer to the main pole tip, or ABS, are more effective than coil turns farther back away from the pole tip. Thus, for a coil turn carrying the same amount of current, the closer the coil is to the pole tip the more efficient the coil is at driving the pole tip.

A First Stacked Coil Configuration

FIG. 3is a cross-sectional side view of an upper stacked coil magnetic writer, according to a first embodiment of the invention. A magnetic writer having a stacked coil takes advantage of the better process control capability available with thin film thicknesses, compared to the control capability of vertical gap filling processes. This provides a coil architecture that is easier to scale down to shorter yoke-length write poles. Further, a stacked coil architecture offers more design freedom to concentrate more current density to the front of the main pole, in comparison with the conventional write head200ofFIG. 2in which the coil turns are spread out helically along the length of the main pole, which further enhances the high data rate writing capabilities of the write head.

Magnetic writer300comprises a main pole204having a pole tip208aand a yoke208b, a lower return pole206, an upper return pole318, and a stacked coil302. Stacked coil302comprises a plurality of upper stacked coil portions302a,302b,302c, and a plurality of lower coil portions302d,302e,302f. Three upper and lower coil turns are depicted inFIG. 3for purposes of explanation, however, embodiments of the invention are not limited to three coil turns, and the number of coil turns may vary from implementation to implementation.

Upper coil portions302a,302b,302care referred to as a “stacked” configuration, because each successive coil turn in the direction away from the main pole is stacked on the preceding coil turn which is closer to the main pole. Therefore, successive layers of one or more coil turn are supported by a preceding layer of one or more coil turn, with a layer of alumina insulation (e.g., atomic layer deposited) between each layer of coil, providing a structural foundation for successively manufactured layer(s) of one or more coil turn. Not only does this stacked configuration provide a practical, readily manufacturable configuration for a short yoke length write head, because it can be configured to need and use less space along the direction of the main pole toward the ABS, but it also concentrates more of the coil structure (and, thus, more current) closer to the main pole tip208athan does the conventional coil configuration shown inFIG. 2. Both of the foregoing features provide for a higher data rate, i.e., faster, write head in comparison with the coil configuration shown inFIG. 2.

Manufacturing a Magnetic Write Head Stacked Coil

FIG. 4is a flow diagram illustrating a method of manufacturing a stacked coil magnetic writer having upper stacked coil portions, according to a first embodiment of the invention.FIG. 5is a cross-sectional side view of a first stage of an upper stacked coil magnetic writer, according to the first embodiment of the invention. Having introduced the concept of a stacked coil architecture for a magnetic write head, in reference to magnetic writer300ofFIG. 3, a method for manufacturing such a stacked coil is now described with reference toFIG. 4and the partial writer500ofFIG. 5. Conventional techniques may be used for the manufacturing of the read head, the lower return pole206, and lower coil portions302d,302e,302f.

At block402, a plating seed layer is deposited. For example, an electrically conductive seed layer312a(FIG. 5), such as copper or gold, is deposited to provide electrical conducting layer for the subsequent plating process.

At block404, a photolithographic process is applied on the seed layer (e.g., seed layer312aofFIG. 5), to enable the plating of a coil lead (also referred to herein as a “coil portion”), on a portion of the seed layer.

As known in the art, photolithography is a process used to pattern parts of a thin film or the bulk of a substrate. The photolithography process uses light to transfer a pattern from a photomask to a light-sensitive chemical photoresist on the substrate. A series of chemical treatments then either engraves the exposure pattern into the material or enables deposition of a new material in the desired pattern. Here, the photolithographic process is utilized to define the shape, or footprint, of the coil lead that is subsequently plated (e.g., at block406).

At block406, copper coil is plated through the defined pattern. For example, upper coil portion302a(FIG. 5) is plated onto the portion of the seed layer312a(FIG. 5).

At block408, the remainder of the seed layer applied at block402is removed. That is, the seed layer312a(FIG. 5), in the area that was not plated, is now removed. For example, ion milling or sputter etching processes may be utilized to remove the remainder of the seed layer that was used for electrical connection for the copper plating process.

At block410, alumina is deposited over the coil lead using atomic layer deposition (ALD) process. For example, an alumina (aluminum oxide) layer314a(FIG. 5) is deposited over upper coil portion302a(FIG. 5), using ALD process. Consequently, there is now an alumina insulation layer between upper coil portion302aand any subsequent layers of writer300(FIG. 3), such as a subsequent seed layer for plating upper coil portion302b(FIG. 3).

As known in the art, atomic layer deposition is a thin film deposition technique that is based on the sequential use of a gas phase chemical process. ALD is a self-limiting (the amount of film material deposited in each reaction cycle is constant), sequential surface chemistry that deposits conformal thin-films of materials onto substrates of varying compositions.

Next, the alumina is then removed from areas in which it is undesirable, such as areas that will serve as contact areas to the lower coils, and for an upper return pole (see upper return pole318ofFIG. 3), such as the area above wrap-around shield (WAS)209and the area of the back gap203(FIG. 3).

After this first stage of the manufacturing process of writer300(FIG. 3), the apparatus is now in the form of partial writer500ofFIG. 5. To lay down any additional stacked upper coil portions, such as upper coil portion302band upper coil portion302c(FIG. 3), a similar process as that depicted inFIG. 4follows. As such, a second plating seed layer is deposited over the alumina layer314a(similar to block402) and a photolithographic process is applied to this second seed layer to enable plating of upper coil portion302bon a portion of the second seed layer (similar to blocks404and406). Similarly, the remainder of the seed layer is removed (similar to block408), and an alumina layer314bis deposited over the coil lead302busing atomic layer deposition (ALD) process (similar to block410). The alumina layer is then removed from the contact area to the lower coil and the upper return pole.

Returning toFIG. 3, likewise, to manufacture upper coil portion302cstacked on top of upper coil portion302b, similar steps to blocks402-410(FIG. 4) are performed. Each upper coil portion302a,302b,302cis connected to one or more corresponding lower coil portion302d,302e,302fvia one or more electrically conductive tab, thereby completing an electrically contiguous coil structure. Additionally, at least two of the coil portions302a,302b,302c,302d,302e,302fare connected to a lead for electrically connecting with a slider electrical connection pad.

Once upper coil portion302cis plated and covered in alumina layer314c, then upper return pole318is manufactured. According to an embodiment, to manufacture the upper return pole318, the alumina is removed from the area above wrap-around shield (WAS)209and the area of the back gap203. A NiFe plating seed layer316is deposited over alumina layer314cand a photolithographic process applied to the seed layer316to prepare it for the plating process. A soft magnetic, conformal, upper return pole318is then plated over the seed layer316, with upper return pole318having contact areas with WAS209and back gap203, thus completing writer300. Use of ALD process for the alumina layers, compared to RF sputtering, provides for highly conformal alumina layers314a,314b,314cand, likewise, for a highly conformal upper return pole318. The highly conformal upper return pole318provides an optimally short return path for the magnetic flux which further enhances the write data rate of writer300. Consequently, the write data rate performance of magnetic writer300should be expected to exceed the write data rate of conventional writer200(FIG. 2).

A Second Stacked Coil Configuration

FIG. 6is a cross-sectional side view of an upper and lower stacked coil magnetic writer, according to a second embodiment of the invention. Similarly to magnetic writer300(FIG. 3), magnetic writer600comprises a main pole204having a pole tip208aand a yoke208b, a lower return pole206, an upper return pole318, and a stacked coil602. However, stacked coil602comprises a plurality of stacked upper coil portions602a,602b,602c, as well as a plurality of stacked lower coil portions602d,602e,602f. Three upper and lower coil turns are depicted inFIG. 6for purposes of explanation, however, embodiments of the invention are not limited to three coil turns, and the number of coil turns may vary from implementation to implementation. The write data rate performance of magnetic writer600should be expected to exceed the write data rate of conventional writer200(FIG. 2), as well as the write data rate of magnetic writer300, but at the expense of manufacturing complexity.

The upper coil portions602a,602b,602cof magnetic writer600are configured and manufactured the same as, or similar to, magnetic writer300(FIG. 3). As magnetic writer600includes stacked lower coil portions602d,602e,602frather than a conventional lower coil portions202d,202e,202f(FIG. 2), the same or similar method of manufacturing (e.g.,FIG. 4) stacked upper coil portions602a,602b,602c(and302a,302b,302c) can be applied to the stacked lower coil portions602d,602e,602f. Therefore, the stacked lower coil of writer600also comprises ALD-deposited alumina layers314d,314e,314f, for insulation purposes, over each of the respective lower coil portions602d,602e,602f.

A Third Stacked Coil Configuration

FIG. 7is a cross-sectional side view of an upper stacked coil magnetic writer, according to a third embodiment of the invention.

Magnetic writer700comprises a main pole204having a pole tip208aand a yoke208b, a lower return pole206, an upper return pole718, and a stacked coil702. Stacked coil702comprises a plurality of stacked upper coil portions702a,702b,702c, and a plurality of lower coil portions. Three upper and lower coil turns are depicted inFIG. 7for purposes of explanation, however, embodiments of the invention are not limited to three coil turns, and the number of coil turns may vary from implementation to implementation.

Upper coil portions702a,702b,702care referred to as a “stacked” configuration, because one or more coil turn in the direction away from the main pole is stacked on the preceding one or more coil turn which is closer to the main pole. Therefore, successive layers of one or more coil turn are supported by a preceding layer of one or more coil turn, with a very thin layer of alumina insulation between each layer of coil, providing a structural foundation for successively manufactured layer(s) of one or more coil turn. Not only does this stacked configuration provide a practical, readily manufacturable configuration for a short yoke length write head, because it can be configured to need and use less space along the direction of the main pole toward the ABS, but it also concentrates more of the coil structure (and, thus, more current) closer to the main pole tip208athan does the conventional coil configuration shown inFIG. 2. Both of the foregoing features provide for a higher data rate, i.e., faster, write head in comparison with the coil configuration shown inFIG. 2.

FIG. 8is a cross-sectional side view of a first stage of an upper stacked coil magnetic writer, according to the third embodiment of the invention. The same or similar process as illustrated inFIG. 4can be used to manufacture magnetic writer700(FIG. 7). That is, to lay down the first layer of upper coil portions, i.e., upper coil portion702aand upper coil portion702b, a similar process as that depicted inFIG. 4may be followed. As such, a first plating seed layer712ais deposited (similar to block402), a photolithographic process is applied to this first seed layer to enable plating of upper coil portions702aand702bon a portion of the first seed layer (similar to block404), and each of the copper coil leads702a,702bis plated on the portion of the first seed layer from which seed material was previously removed (similar to block406). Similarly, the remainder of the seed layer is removed (similar to block408), and an alumina layer714ais deposited over the first layer of coil leads702a,702busing atomic layer deposition (ALD) process (similar to block410).

After this first stage of the manufacturing process of writer700(FIG. 7), the apparatus is now in the form of partial writer800ofFIG. 8. To lay down any additional stacked upper coil portions, such as upper coil portion702c(FIG. 7), a similar process as that depicted inFIG. 4follows. Alumina which covered the lower coil contact area is removed first. As such, a second plating seed layer is deposited over the alumina layer714a(similar to block402), a photolithographic process is applied to this second seed layer to enable plating of upper coil portion702con a portion of the second seed layer (similar to block404), and copper coil lead702cis plated on the portion of the second seed layer opened by the photolithographic process (similar to block406). Similarly, the remainder of the seed layer is removed (similar to block408), and an alumina layer714bis deposited over the coil lead702cusing atomic layer deposition (ALD) process (similar to block410). Each upper coil portion702a,702b,702cis connected to one or more corresponding lower coil portion via one or more electrically conductive tab, thereby completing an electrically contiguous coil structure.

Once upper coil portion702cis plated and covered in alumina layer714b, then upper return pole718is manufactured similarly as described in reference toFIG. 3, whereby a NiFe plating seed layer is deposited over alumina layer714band a photolithographic process applied to the seed layer to prepare it for the plating process. A soft magnetic, conformal, upper return pole718is then plated over the seed layer. Use of ALD process for the alumina layers provides for highly conformal alumina layers714a,714b, and, likewise, for a highly conformal upper return pole718, which provides an optimally short return path for the magnetic flux which further enhances the write data rate of writer700.

Alternative Stacked Coil Configurations

FIG. 9is a cross-sectional side view of an upper stacked coil magnetic writer, according to a fourth embodiment of the invention. Magnetic writer900comprises a main pole204having a pole tip208aand a yoke208b, a lower return pole206, an upper return pole918, and a stacked coil902. Stacked coil902comprises a plurality of stacked upper coil portions902a,902b,902c, and a plurality of lower coil portions. Three upper and lower coil turns are depicted inFIG. 9for purposes of explanation, however, embodiments of the invention are not limited to three coil turns, and the number of coil turns may vary from implementation to implementation. Upper coil portions902a,902b,902care referred to as a “stacked” configuration, because one or more coil turn in the direction away from the main pole is stacked on the preceding one or more coil turn which is closer to the main pole. Therefore, successive layers of one or more coil turn are supported by a preceding layer of one or more coil turn, with a very thin layer of alumina insulation between each layer of coil, providing a structural foundation for successively manufactured layer(s) of one or more coil turn.

For writer900, each upper coil portion902a,902b,902chas a proximate end that is proximate to the air bearing surface (the left hand side ofFIG. 9), and each successive upper coil portion away from write pole204has a larger cross-section than the previous upper coil portion. For example, coil portion902chas a larger and wider cross-section than coil portion902b, which has a larger and wider cross-section than902a. Further according to the embodiment ofFIG. 9, the proximate end of each said successive upper coil portion is farther away from the air bearing surface than the proximate end of the previous upper coil portion. For example, coil portion902cis farther from the ABS than coil portion902b, which is farther from the ABS than902a. Thus, coil portion902ahas more of its current closer to the ABS and, hence, closer to the pole tip208a, which maximizes writing efficiency. Additionally, coil portion902chas some of its current close to the ABS and pole tip208a, increasing its writing efficiency, but also has a larger cross-section to reduce the overall electrical resistance of the coil902. Therefore, coil902cstrikes a balance between its contribution to writing efficiency and coil resistance.

A similar process as illustrated inFIG. 4can be used to manufacture magnetic writer900. That is, to lay down the successive layers of upper coil portions, i.e., upper coil portion902aand then upper coil portion902band then upper coil portion902c, a similar process as that depicted inFIG. 4may be followed, with some process modification as needed to create support for the top coil portion overhanging beyond the bottom coil. Then upper return pole918is manufactured similarly as described in reference toFIG. 3.

FIG. 10is a cross-sectional side view of an upper stacked coil magnetic writer, according to a fifth embodiment of the invention. Magnetic writer1000comprises a main pole204having a pole tip208aand a yoke208b, a lower return pole206, an upper return pole1018, and a stacked coil1002. Stacked coil1002comprises a plurality of stacked upper coil portions1002a,1002b,1002c, and a plurality of lower coil portions. Three upper and lower coil turns are depicted inFIG. 10for purposes of explanation, however, embodiments of the invention are not limited to three coil turns, and the number of coil turns may vary from implementation to implementation. Upper coil portions1002a,1002b,1002care referred to as a “stacked” configuration, because one or more coil turn in the direction away from the main pole is stacked on the preceding one or more coil turn which is closer to the main pole. Therefore, successive layers of one or more coil turn are supported by a preceding layer of one or more coil turn, with a very thin layer of alumina insulation between each layer of coil, providing a structural foundation for successively manufactured layer(s) of one or more coil turn.

For writer1000, each upper coil portion1002a,1002b,1002cis similar to each corresponding upper coil portion902a,902b,902c(FIG. 9) because each successive upper coil portion away from write pole204has a larger cross-sectional area than the previous upper coil portion. For example, coil portion1002chas a larger and wider cross-section than coil portion1002b, which has a larger and wider cross-section than1002a. Also, the proximate end of each successive upper coil portion1002a,1002b,1002cis farther away from the air bearing surface than the proximate end of the previous upper coil portion. For example, coil portion1002cis farther from the ABS than coil portion1002b, which is farther from the ABS than1002a. Further for writer1000, one or more of the upper coil portions1002a,1002b,1002ccomprises a leg extending in the direction of the write pole204.

Thus, coil portion1002ahas more of its current closer to the ABS and, hence, closer to the pole tip208a, which maximizes writing efficiency. Additionally, coil portion1002chas some of its current close to the ABS and pole tip208a, increasing its writing efficiency, but also has a larger cross-section to reduce the overall electrical resistance of the coil1002. Therefore, coil1002cstrikes a balance between its contribution to writing efficiency and coil resistance.

A similar process as illustrated inFIG. 4can be used to manufacture magnetic writer1000. That is, to lay down the successive layers of upper coil portions, i.e., upper coil portion1002aand then upper coil portion1002band then upper coil portion1002c, a similar process as that depicted inFIG. 4may be followed. Then upper return pole1018is manufactured similarly as described in reference toFIG. 3.

FIG. 11is a cross-sectional side view of an upper stacked coil magnetic writer, according to a sixth embodiment of the invention. Magnetic writer1100comprises a main pole204having a pole tip208aand a yoke208b, a lower return pole206, an upper return pole1118, and a stacked coil1102. Stacked coil1102comprises a plurality of stacked upper coil portions1102a,1102b,1102c, and a plurality of lower coil portions. Three upper and lower coil turns are depicted inFIG. 11for purposes of explanation, however, embodiments of the invention are not limited to three coil turns, and the number of coil turns may vary from implementation to implementation. Upper coil portions1102a,1102b,1102care referred to as a “stacked” configuration, because one or more coil turn in the direction away from the main pole is stacked on the preceding one or more coil turn which is closer to the main pole. Therefore, successive layers of one or more coil turn are supported by a preceding layer of one or more coil turn, with a very thin layer of alumina insulation between each layer of coil, providing a structural foundation for successively manufactured layer(s) of one or more coil turn.

For writer1100, each upper coil portion1102a,1102b,1102cis similar to each corresponding upper coil portion902a,902b,902c(FIG. 9) because the proximate end of each successive upper coil portion1102a,1102b,1102cis farther away from the air bearing surface than the proximate end of the previous upper coil portion. For example, coil portion1102cis farther from the ABS than coil portion1102b, which is farther from the ABS than1102a. By contrast with upper coil portions902a,902b,902c, for writer1100each said upper coil portion has an approximate equal cross-sectional area.

A similar process as illustrated inFIG. 4can be used to manufacture magnetic writer1100. That is, to lay down the successive layers of upper coil portions, i.e., upper coil portion1102aand then upper coil portion1102band then upper coil portion1102c, a similar process as that depicted inFIG. 4may be followed, with some process modification as needed to create support for the top coil portion overhanging beyond the bottom coil. Then upper return pole1118is manufactured similarly as described in reference toFIG. 3.