# Patent

## Title
Method for fabricating a magnetic writer having a gradient in saturation magnetization of the shields

## Abstract

A method provides a magnetic transducer having a media-facing surface (MFS). The method includes providing a pole, providing a side gap, providing coil(s) for energizing the pole and providing side shield(s). A portion of the pole resides at the MFS. The side gap is between the pole and the side shield(s). The side shield(s) have a gradient in a saturation magnetization such that the saturation magnetization increases in a yoke direction perpendicular to the MFS. The step of providing the side shield(s) further includes providing a nonmagnetic structure having a side surface parallel to the MFS and providing at least one side shield layer. A portion of the side shield layer(s) are on the side surface. The portion of the side shield layer(s) has the gradient in the saturation magnetization. At least part of the side shield being formed by the portion of the side shield layer(s).

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part of co-pending patent application Ser. No. 14/575,090, filed Dec. 18, 2014, entitled “Magnetic Writer Having a Gradient in Saturation Magnetization of the Shields”, and assigned to the assignee of the present application.


BACKGROUND
FIGS. 1A and 1B air-bearing surface (ABS) and plan views, respectively, of a conventional magnetic recording transducer 10. The magnetic recording transducer 10 may be a perpendicular magnetic recording (PMR) head. The conventional transducer 10 includes an underlayer 12 that may include a leading shield, side gap 14, side shields 16, top gap 17, a top (or trailing) shield 18 and main pole 20.
The main pole 20 resides on an underlayer 12 and includes sidewalls 22 and 24. The sidewalls 22 and 24 of the conventional main pole 20 form an angle with the down track direction at the ABS. The side shields 16 are separated from the main pole 20 by a side gap 14. The side shields 16 extend at least from the top of the main pole 20 to the bottom of the main pole 20. The side shields 16 also extend a distance back from the ABS. The gap 14 between the side shields 16 and the main pole 20 may have a substantially constant thickness. Thus, the side shields 16 are conformal with the main pole 20.
Although the conventional magnetic recording transducer 10 functions, there are drawbacks. In particular, the conventional magnetic recording head 10 may not perform sufficiently at higher recording densities or for some recording schemes. Accordingly, what is needed is a system and method for improving the performance of a magnetic recording transducer.



BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
FIGS. 1A-1B depict ABS and plan views of a conventional magnetic recording head.
FIGS. 2A, 2B and 2C depict side, ABS and plan views of portions of an exemplary embodiment of a magnetic recording disk drive with side shields having a gradient in saturation magnetization.
FIG. 3 is a flow chart depicting an exemplary embodiment of a method for providing a magnetic recording write apparatus having a gradient in side shield saturation magnetization.
FIG. 4 is a flow chart depicting an exemplary embodiment of a method for providing a side shield having a gradient in side shield saturation magnetization.
FIG. 5 is a flow chart depicting another exemplary embodiment of a method for providing a side shield having a gradient in side shield saturation magnetization.
FIGS. 6A-6B through 19A-19D depict another exemplary embodiment of a portion of a magnetic recording transducer with side shields having a gradient in saturation magnetization during fabrication.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The trend in magnetic recording is to higher densities. For such higher recording densities, a full wrap around shield may be used. For example, the trailing shield 18, side shields 16 and a leading shield in the underlayer 12 may be used in the transducer 10 depicted in FIGS. 1A-1B. The trailing shield 18 may have a high saturation magnetization of approximately 2.3 T. The high saturation magnetization may be desired to provide the desired field gradient. The leading shield of the underlayer 12 may have a low saturation magnetization on the order of 1 T. The low saturation magnetization of the leading shield may aid in balancing on and off track performance. The side shield 16 has a higher saturation magnetization of approximately 2 T.
In some cases, different writing schemes are used to facilitate higher density recording. For example, a shingle recording scheme may be desired to be used at higher areal densities. In shingle recording, successive tracks partially overwrite previously written tracks in one direction only. Part of the overwritten tracks, such as their edges, are preserved as the recorded data. In shingle recording, a higher side shield saturation magnetization may be desired.
It has been determined that there may be issues in high density recording for the configurations and writing schemes described above. For the full wraparound shield described above, a mismatch between the saturation magnetizations of the side shield 16 and the trailing shield 18 may result in flux leakage at the interface between the side shield 16 and the trailing shield 18. This flux leakage may result in wide area track erasure (WATER) issues. For shingle recording, the higher saturation magnetization side shield may shunt flux from the main pole 20. Writing may thus be degraded. In addition, switching of the main pole 20 is a dynamic process. This switching may perturb the domain structure of the side shields 16 and result in magnetic poles in the side shields 16 at the ABS and motions of domain walls with in the side shield 16. These also result in WATER issues. Consequently, it has been determined that there are unaddressed issues in recording at higher areal densities.
While the various embodiments disclosed are applicable to a variety of data storage devices such as magnetic recording disk drives, solid-state hybrid disk drives, networked storage systems etc., for the sake of illustration the description below uses disk drives as examples.
FIGS. 2A, 2B and 2C depict various views of an exemplary embodiment of a magnetic write apparatus. In the embodiment shown, the data storage device is disk drive. FIG. 2A depicts a side view of the disk drive including a magnetic write apparatus 100 that is a magnetic write transducer in the embodiment shown. FIG. 2B depicts a media-facing surface view. In the embodiment shown, the magnetic write apparatus is a transducer 100. Thus, the media-facing surface is the air-bearing surface (ABS). FIG. 2C depicts a plan view of the transducer 100. For clarity, FIGS. 2A-2C are not to scale. For simplicity not all portions of the disk drive and transducer 100 are shown. In addition, although the disk drive and transducer 100 are depicted in the context of particular components other and/or different components may be used. For example, circuitry used to drive and control various portions of the disk drive is not shown. For simplicity, only single components are shown. However, multiples of each components and/or their sub-components, might be used. The disk drive may be a perpendicular magnetic recording (PMR) disk drive. However, in other embodiments, the disk drive may be configured for other types of magnetic recording included but not limited to heat assisted magnetic recording (HAMR).
The disk drive includes a media 102 and a slider 104 on which the transducer 100 has been fabricated. Although not shown, the slider 104 and thus the transducer 100 are generally attached to a suspension. In general, the slider 104 includes the write transducer 100 and a read transducer (not shown). However, for clarity, only the write transducer 100 is shown.
The transducer 100 includes an underlayer 106, a gap 108, a main pole 110, coil(s) 120, side shields 130 and optional trailing shield 140. The underlayer 106 may include a bottom (or leading) shield. The coil(s) 120 are used to energize the main pole 110. Two turns are depicted in FIG. 2A. Another number of turns may, however, be used. Note that only a portion of the coil(s) 120 may be shown in FIG. 2A. If, for example, the coil(s) 120 is a spiral, or pancake, coil, then additional portions of the coil(s) 120 may be located further from the ABS. Further, additional coils may also be used.
The main pole 110 is shown as having a top wider than the bottom. The main pole 110 thus includes sidewalls having sidewall angles that are greater than or equal to zero. In an embodiment, these sidewall angles differ at different distances from the ABS. In other embodiments, other geometries may be used. For example, the top may be the same size as or smaller than the bottom. The sidewall angles may vary in another manner. The main pole 110 is depicted as having a trapezoidal shape including a flat bottom at the ABS. In other embodiment, the main pole 110 may have another shape including but not limited to a triangle at the ABS. In some embodiments, the main pole 110 may have leading surface bevel and/or a trailing surface bevel. Thus, the main pole 110 may be shorter in the down track direction at the ABS than at location(s) recessed from the ABS.
The gap layer 108 may include one or more sublayers as well as a seed layer. Further, although depicted as a single gap surrounding the main pole 110, the gap 108 may include separate side gaps (between the mail pole 110 and side shields 130) and write gap (between the main pole 110 and trailing shield 140). In addition, although depicted as symmetric, the gap 108 may be asymmetric. For example, the gap between a side of the main pole 110 and one side shield may be wider than the gap between the opposite side of the main pole 110 and the other side shield.
The transducer 100 also includes side shields 130. The side shields 130 may be magnetically and, in some embodiments, physically connected with the trailing shield 140 and leading shield of the underlayer 106. In such embodiments, a full wraparound shield is formed. In other embodiments, the side shields 130 may be physically and/or magnetically disconnected from the trailing shield 140 and/or the leading shield of the underlayer 106. The side shields 130 are also depicted as symmetric in the cross track direction. In other embodiments, asymmetries in the cross track direction may be present.
As can be seen in FIG. 2C, the side shields 130 have a gradient in saturation magnetization (Bs) such that the saturation magnetization increases in a yoke direction perpendicular to the ABS. In some embodiments, the saturation magnetization increase monotonically with distance from the ABS. In other words, the Bs increases, without any decreases, with distance from the ABS. This increase may be linear, step-wise, or described in another manner. In other embodiments, the increase in saturation magnetization need not be monotonic and/or need not be described by a well-known function. Thus, in some embodiments, the saturation magnetization of portions of the side shields 130 recessed from the ABS is greater than the saturation magnetization of portions of the side shields 130 at the ABS. In some embodiments, the saturation magnetization of portions of the leading shield 106 recessed from the ABS is greater than the saturation magnetization of portions of the leading shield 106 at the ABS. Similarly, in some embodiments, the saturation magnetization of portions of the trailing shield 140 recessed from the ABS is greater than the saturation magnetization of portions of the trailing shield 140 at the ABS. Thus, at least the side shields 130 have a saturation magnetization that increases with increasing distance from the ABS. In some embodiments, the leading shield 106 and/or trailing shield 140 may also have a saturation magnetization that changes with distance from the ABS. In alternate embodiments, the gradient might be different than described above. For example, the saturation magnetization might decrease with distance from the ABS.
The gradient in saturation magnetization may be achieved in a number of ways. In some embodiments, the concentration of various constituents in the alloy(s) of the side shields 130, leading shield 106 and/or trailing shield 140 may be varied such that Bs increases with increases distance from the ABS in the yoke direction. In other embodiments, regions of different saturation magnetizations may be provided. For example, a layer closest to and including the ABS may be an alloy having one saturation magnetization. The next layer in the yoke direction may be another alloy having another higher Bs, and so on. For example, in some embodiments, the saturation magnetization of the side shields 130 at the ABS may be at least 1 T and not more than 2 T. In some such embodiments, the Bs is not more than 1.6 T. In other embodiments, Bs at the ABS is at least 1 T and not more than 1.2 T. Further from the ABS, the saturation magnetization is greater. For example, Bs may be greater than 2 T some distance from the ABS. In some embodiments, Bs is at least 2.3 T at the back surface of the side shields 130 furthest from the ABS. The leading shield 106 and trailing shield 140 may be similarly configured. In other embodiments, the variations in the saturation magnetization of the leading shield 106 and/or trailing shield 140 may differ from that of the side shields 130. In some embodiments, the saturation magnetizations of the shields 106, 130 and 140 may match throughout the shields. In other cases, the saturation magnetizations of the shields 106, 130 and 140 may be different in all locations. In still other embodiments, the saturation magnetizations of the shields 106, 130 and 140 may be the same in some locations, but different in other locations. For example, the trailing shield 140 may have a saturation magnetization of at least 2 T at the ABS and at least 2.3 T some distance from the ABS. The side shields 130 might have a saturation magnetization of 1-1.2 T at the ABS and 2.3 T further from the ABS. The interfaces between the regions of different saturation magnetization may be at some angle less than ninety degrees from the ABS. In some such embodiments, the layers having different saturation magnetizations have interfaces that are parallel to the ABS. In some embodiments, the saturation magnetization is constant in planes parallel to the ABS. For example, the Bs does not vary in the down track and/or cross track directions for a plane parallel to the ABS. In other embodiments, Bs may vary along the down track and/or cross track directions. For example, the saturation magnetization may decrease with increasing distance from the pole 110 in the cross track direction. In some embodiments, the saturation magnetization of the side shields 130 may the same as that of the main pole 110 (e.g. 2.4 T) near the main pole 110. The saturation magnetization of the side shields 130 follows a gradient in the cross-track direction, decreasing to 1.0 T near the edges furthest from the main pole 110.
Performance of the transducer 100 and disk drive may be improved by the side shields 130 having a gradient in the saturation magnetization. Because portion(s) of the side shields 130 closest to the ABS has a lower magnetic moment, flux shunting may be reduced. However, portion(s) the side shields 130 further from the ABS have a higher saturation magnetization. Similar benefits might be achieved by configuring the leading shield 106 and/or the trailing shield 140 with a gradient in saturation magnetization such that the saturation magnetization increases in the yoke direction. Consequently, the gradient in the field from the pole may be improved. This increase may be particularly relevant for shingle recording. The increased saturation magnetization of portion(s) of the side shields 130 recessed from the main pole 110 may be less affected by the dynamic nature of switching of the main pole 110. The reduced saturation magnetization of the side shields 130 allows the side shields 130 to be less affected the return field from the media 102. These features may help address WATER and other issues. Thus, performance of the transducer 100 may be improved.
FIG. 3 depicts an exemplary embodiment of a method 200 for providing a magnetic recording transducer or analogous data storage device. For simplicity, some steps may be omitted, interleaved, performed in another order and/or combined. The method 200 may be used to fabricate multiple magnetic recording transducers at substantially the same time. The method 200 is described in the context of the magnetic transducer 100. The method 200 may also be used to fabricate other magnetic write apparatus. The method 200 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 200 also may start after formation of other portions of the magnetic recording transducer. For example, the method 200 may start after the underlayer, optionally including a leading shield, has been formed.
The main pole 110 is formed, via step 202. In some embodiments, step 202 includes forming a trench in one or more nonmagnetic layers. For example, one or more reactive ion etches (RIEs) may form the trench. The trench has a shape and location that corresponds to the pole. In other embodiments the trench may be provided in the side shields. Magnetic material(s) for the pole are deposited. The transducer may then be planarized. A leading and/or trailing edge bevel(s) may optionally be formed on the leading surface (bottom) and/or trailing surface (top) of the main pole.
The side gap 108 is provided, via step 204. Step 204 may include depositing a Ru layer, for example via chemical vapor deposition, sputtering or another method. Additional layer(s) may also be provided. In some embodiments, step 204 is performed before step 202. For example, if the side shields 130 are formed first, step 204 may include removing a portion of the material(s) for the side shield 130 to form a trench therein. The materials for the side gap 108 would then be deposited. The side gap would be formed by the portion of the side gap materials that reside in the trench. The pole 110 formed in step 202 may also reside in the trench. Thus, the main pole 110 is provided on the side gap 108 in such embodiments. In other embodiments, the main pole 110 might be fabricated first and the side gap 108 formed on the main pole 110.
The coil(s) 120 for the main pole are provided, via step 206. Step 206 may be interleaved with other steps of the method 200. For example, portions of the coil(s) 120 may be formed before the main pole 110 and side shields 130. The coil(s) formed may be helical coil(s) or spiral coils.
The side shields 130 having the gradient in saturation magnetization is provided, via step 208. The step of providing the side shield further includes providing a nonmagnetic structure having a side surface parallel to the ABS. Stated differently, at least a portion of the side surface is parallel to the ABS and the side surface is generally oriented in the same direction in the ABS. However, the side surface need not be completely flat or perfectly parallel to the ABS. In some embodiments, the nonmagnetic structure is a metal structure that is removable, for example via an ion mill or reactive ion etch (RIE). The nonmagnetic structure may thus be a sacrificial structure. In some embodiments, the nonmagnetic structure may be formed of NiP, Cu, Ru, and/or NiCr.
One or more shield layers are also deposited as part of step 208. The shield layer(s) may be conformally deposited, for example via plating or sputtering. A seed layer may also be deposited prior to the shield layer(s). At least part of the shield layer(s) reside on the side surface of the nonmagnetic structure. As a result, portions of the shield layer(s) have interfaces that are substantially parallel to the ABS. One or more of the shield layer(s) may also have a composition that is varied during deposition. If multiple shield layers are used, the shield layers have different compositions and different saturation magnetizations. Thus, the shield layer(s) may have a gradient in saturation magnetization in a direction substantially perpendicular to the side surface of the nonmagnetic structure. As a result, a side shield having a gradient in saturation magnetization in the yoke direction is fabricated. In embodiments in which the side gap 108 and main pole 110 are formed on the side shield layer(s), a portion of the side shield on which the main pole 110 resides may form the leading shield 106.
Using the method 200, a magnetic transducer having improved performance may be fabricated. Because of the gradient in the saturation magnetization of the side shields 130 the benefits thereof may be achieved.
FIG. 4 depicts an exemplary embodiment of a method 210 for providing a side shield having a gradient in saturation magnetization. For simplicity, some steps may be omitted, interleaved, performed in another order and/or combined. The method 210 may be used to fabricate multiple magnetic recording transducers at substantially the same time. The method 210 is described in the context of the side shields 130 of the magnetic transducer 100. The method 210 may also be used to fabricate other side shields of other magnetic write apparatus. The method 210 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 210 also may start after formation of other portions of the magnetic recording transducer. For example, the method 210 may start after the underlayer has been formed.
A nonmagnetic structure having a side surface parallel to the ABS is provided, via step 212. As discussed above, the side surface being parallel to the ABS indicates that the side surface is generally oriented in the same direction in the ABS. However, as discussed above, the side surface need not be completely flat or perfectly parallel to the ABS. In some embodiments, the nonmagnetic structure may be formed of NiP, Cu, Ru, and/or NiCr. Step 212 may include providing a mask having an aperture in the desired shape and location as the nonmagnetic structure. The nonmagnetic metal may then be deposited and the mask removed. For example, a photoresist mask may be used and the nonmagnetic metal may be plated. In some embodiments, the nonmagnetic structure is oriented such that the side shield is desired to be built on the side surface with the lowest saturation magnetization closest to the nonmagnetic structure. In some such embodiments, the nonmagnetic structure may be on a portion of the wafer on which the transducer 100 is fabricated that does not become part of the final device 100. In other embodiments, the highest saturation magnetization may be deposited first. In some such embodiments, the nonmagnetic structure may be located in the yoke direction from the ABS. In such embodiments, some part of the nonmagnetic structure may remain in the final device 100. However, other configurations are possible.
One or more shield layers are deposited, via step 214. The shield layer(s) may be conformally deposited in step 214, for example via plating or sputtering. Step 214 may also include depositing a seed layer prior to the shield layer(s). At least part of the shield layer(s) reside on the side surface of the nonmagnetic structure. As a result, portions of the shield layer(s) have interfaces that are substantially parallel to the ABS. In addition, the growth direction of the side shield layer(s) is generally outward (in the yoke direction) from the side surface of the nonmagnetic structure. Thus, shield layers having different saturation magnetizations may be deposited. One or more of the shield layer(s) may also have a composition that is varied during deposition. For example, such a shield layer may be plated in a single plating cell having a plating bath that varies in concentration. Thus, the composition may vary with distance from the side surface of the nonmagnetic structure. As a result, each of the shield layer(s) may have a gradient in saturation magnetization in a direction substantially perpendicular to the side surface of the nonmagnetic structure. If formed of this single shield layer that varies in composition, the side shield may be fabricated in a single plating bath. In addition, if multiple shield layers are used, the shield layers have different compositions and different saturation magnetizations. Thus, the shield layer(s) may have a gradient in saturation magnetization in a direction substantially perpendicular to the side surface of the nonmagnetic structure. As a result, a side shield having a gradient in saturation magnetization in the yoke direction is formed. In embodiments in which the side gap 108 and main pole 110 are formed on the side shield layer(s), a portion of the side shield on which the main pole 110 resides may form the leading shield 106.
The region around the shield layer(s) is refilled with a nonmagnetic material, such as a nonmagnetic insulator, via step 216. Step 216 may include depositing aluminum oxide. The layers may then be planarized, via step 218. Fabrication of the writer may then be completed.
Using the method 210, a magnetic transducer having improved performance may be fabricated. Because of the gradient in the saturation magnetization of the side shields 130 the benefits thereof may be achieved.
FIG. 5 depicts an exemplary embodiment of a method 250 for providing a magnetic transducer having side shields that have a gradient in saturation magnetization such that the saturation magnetization increases in the yoke direction. For simplicity, some steps may be omitted, interleaved, performed in another order and/or combined. The method 250 is also described in the context of providing a magnetic recording transducer 150 depicted in FIGS. 6A-6B through FIGS. 19A-19D depict various views of an exemplary embodiment of a transducer 150 during fabrication using the method 250. The method 250 may be used to fabricate multiple magnetic recording transducers at substantially the same time. The method 250 may also be used to fabricate other data storage devices. The method 250 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 250 also may start after formation of other portions of the magnetic recording transducer or disk drive of which the magnetic recording transducer is a part. For example, the method 250 may start after a read transducer, return pole/shield and/or other structure(s) have been fabricated.
A seed layer is provided, via step 252. The seed layer is generally desired to be conductive to allow plating of side shield layer(s). The seed layer may be blanket deposited in an area including but not limited to the region in which the side shields. Alternatively, portions of the magnetic transducer that have already been fabricated may be covered by a mask, the seed layer deposited, and the mask removed. The seed layer might be nonmagnetic. Such a seed layer might include Ru, NiCr and/or NiCu. Alternatively, the seed layer might be magnetic.
A nonmagnetic metal structure is provided on the on the seed layer, via step 254. The nonmagnetic metal structure has a side surface parallel to the ABS and a top surface. As discussed above, the side surface being parallel to the ABS includes only a portion of the side surface being parallel to the ABS. However, the side surface is generally desired to be oriented along the ABS. FIGS. 6A and 6B, 7A and 7B and 8A and 8B depict the magnetic transducer 150 during step 254. FIGS. 6A-6B depict plans and apex views, respectively, after deposition of the seed layer 152 and formation of a mask 154 having aperture 156 therein. The mask 154 may be a photoresist mask. The aperture 156 has the shape and location of the nonmagnetic structure being formed. The surface at which the ABS will be after lapping is shown as the ABS location. FIGS. 7A and 7B depict plan and apex views, respectively, of the transducer 150 after the metal for the nonmagnetic metal structure 158 has been provided in the aperture 156. The nonmagnetic metal structure 158 may include one or more of NiP, Ru, NiCr and Cu. In some embodiments, NiP may be desired to be used. FIGS. 8A-8B depict plan and ABS views, respectively, of the transducer 150 after the mask 154 has been removed. In some embodiments, the photoresist mask 154 is stripped. Thus, the nonmagnetic metal structure 158 remains. The nonmagnetic metal structure 158 includes side surface 159. As can be seen in FIG. 8A, the side surface 159 is not perfectly parallel to the ABS location, but is generally oriented along the ABS location. A portion of the side surface 159 near the center of the drawings is parallel to the ABS location. In the embodiment shown, the side surface 159 is curved in the yoke direction. In other embodiments the side surface 159 may be flat.
A portion of the seed layer 152 that is uncovered by the nonmagnetic metal structure 158 is removed, via step 256. The exposed portion of the seed 152 may be removed via ion milling. FIGS. 9A-9B depict plan and apex views, respectively, of the magnetic transducer 150 after step 256 is completed. Thus, the seed layer 152 remains only under the magnetic structure 158.
A mask that covers a portion of the top surface of the nonmagnetic metal structure 158 is provided, via step 258. Step 258 may include providing a photoresist mask. FIGS. 10A-10B depict plan and apex views of the transducer 150 after step 258 is performed. Thus, a mask 160 that covers part of the top surface of the metal structure 158 has been formed. The desired side surface 159 of the metal structure 158 is still exposed.
At least one side shield layer is conformally deposited, via step 260. The side shield layer(s) may be plated. In alternate embodiments, the side shield layer(s) may be sputtered or deposited in another manner. FIGS. 11A and 11B depict plan and apex views of the transducer 150 after step 260 is performed. Thus, side shield layers 170 are shown. In the embodiment shown, three layers 172, 174 and 176 (collectively 170) have been plated. Thus, the side shield layers 170 have grown out from the metal structure 158, rather than up from the insulating layer below the metal structure. Stated differently, the growth direction for the side shield layers 170 is generally along the yoke direction. Thus, each side shield layer 172, 174 and 176 has a different saturation magnetization. For example, the side shield layer 172, 174 and 176 may be formed of NiFe, CoNiFe and CoFe, respectively. In each side shield layer 172, 174 and 176, the concentration of the constituents may be varied. Thus, each of the side shield layers 172, 174 and 176 may also have a gradient in the saturation magnetization. Note that in an alternate embodiment, each side shield layer 172, 174 and 176 may represent a different range of saturation magnetization of a single layer that has varying concentration(s) of magnetic constituent(s). Thus, the side shield layers 170 have a saturation magnetization that varies in the yoke direction. In the embodiment shown, the saturation magnetization of the side shield layers 170 may decrease closer to the ABS location. In addition, in some embodiments, the saturation magnetization of the side shield layers 170 may have a gradient in the cross-track and/or down track directions.
The mask 160 is removed, via step 262. A photoresist strip may be carried out in step 262. FIGS. 12A and 12B depict plan and apex views of the transducer 150 after step 262 is performed. Thus, the mask 160 has been removed.
One or more nonmagnetic insulating layers are deposited after the mask 160 is removed, via step 264. Thus, a silicon oxide layer or other nonmagnetic layer maybe deposited. The nonmagnetic insulating layer(s) covering the side shield layers 170 and the exposed portion of the nonmagnetic metal structure 158. FIGS. 13A and 13B depict the transducer 150 after step 264 is performed. Thus, a silicon oxide layer 180 is shown. The silicon oxide layer 180 is sufficiently thick to refill the region around the metal structure 158.
The portion of the magnetic transducer 150 that has been fabricated is planarized, via step 266. A chemical mechanical planarization (CMP) may be performed in step 266. Thus, the side shield layer(s) 170 and the nonmagnetic insulating layer such 180 are planarized. FIGS. 14A and 14B depict plan and apex views of the transducer 150 after step 266 is completed. Thus, the silicon oxide layer 180 remains in the regions around the side shield layers 170 and the nonmagnetic metal structure 158. The top of the nonmagnetic metal structure 158 is exposed. Thus, portions of the side shield layers 170 on the nonmagnetic metal structure 158 have been removed.
A trench is formed in the side shield layers 170 and nonmagnetic metal structure 158, via step 268. Thus, part of the side shield layer(s) 170 and nonmagnetic metal structure 158 are removed. A portion of the nonmagnetic insulating layer 180 may also be removed. The trench has a shape and location corresponding to the pole being formed. FIGS. 15A-15C through 17A-17D depict various views of the transducer 150 during step 268. FIGS. 15A, 15B and 15C depict plan, apex and ABS location views, respectively, of the transducer 150 during formation of the mask used in providing the trench. Thus, a hard mask layer 182 has been deposited. The hard mask layer 182 may include Ta. A photoresist mask 184 corresponding to the pole has also been provided using photolithography. An additional hard mask layer 186 has also been deposited. The additional hard mask layer 186 may be Cr. FIGS. 16A, 16B and 16C depict plan, apex and ABS location views, respectively of the transducer after removal of the photoresist mask. Thus, the hard mask layers 182 and 186 having aperture 188 remain. The hard mask layers 182 and 186 form the hard mask for the trench. FIGS. 17A, 17B, 17C and 17D depict plan, apex, ABS location and recessed views, respectively, of the transducer after step 268 is completed. The recessed view is taken along a plane parallel to the ABS, but further into the transducer 150 in the yoke direction. Thus, trench 190 has been formed. The trench 190 is formed in the side shield layers 170, the nonmagnetic structure 158, seed layer 152 and nonmagnetic insulating layer 180. In the embodiment shown, the depth, width and profile of the trench change with distance from the ABS location.
One or more side gap layers are deposited, via step 270. The side gap layer(s) may be blanket deposited. Thus, part of the side gap layer(s) may be in the trench 190, while another portion of the side gap layer(s) are outside of the trench 190. FIGS. 18A, 18B, 18C, and 18D depict plan, apex, ABS and recessed views, respectively, of the transducer 150. Thus, the side gap layer(s) 190 have been deposited. In some embodiments, the side gap layer(s) are conformal. Thus, the pole formed is conformal to the side shields formed by the remaining part of side shield layers 170. In other embodiments, the side gap layer(s) may not form a conformal side gap. For example, the side gap layer(s) may have different thicknesses in different regions and/or may be able to occupy only a portion of the trench 190. Thus, the side gap formed may be conformal or nonconformal. In the embodiment depicted in FIGS. 18A-18D the side gaps are conformal.
The material(s) for the pole are deposited, via step 272. In some embodiments, high saturation magnetization material(s) are provided in step 272. In other embodiments, nonmagnetic layers/structures and/or lower saturation magnetization materials may also be used in the pole. Such materials are provided as part of step 272.
A portion of the pole material(s) external to the trench 190 may be removed, via step 274. Step 274 may include performing another planarization, such as a CMP. FIGS. 19A, 19B, 19C and 19D depict plan, apex, ABS and recessed views, respectively, of the transducer 150 after step 274 is performed. Thus, the pole 194 is shown. In addition, the pole 194 is on the side shield layers 170 at and near the ABS. Thus, the side shield layers 170 form the side shield and a leading shield. In some embodiments, other structures such as a trailing bevel may be formed in the pole 194, via step 276. The write gap may be provided on the pole 194, via step 278. The top shield and coil(s) for energizing the pole 194 are provided, via step 280 and 282, respectively. Fabrication of the transducer 150 may then be completed. For example other structures may be formed and the transducer may be lapped to the ABS.
Using the method 250, the transducer 150 including side shields 170, which also form a leading shield below the pole 194, may be provided. Because the saturation magnetization increases further from the ABS, flux shunting, field gradient, and WATER may be improved. Thus, performance of the transducer 150 may be improved.

## Claims

1. A method for providing a magnetic transducer having media-facing surface (MFS) comprising:
providing a pole, wherein a portion of the pole resides at the WS;
providing a side gap;
providing at least one coil for energizing the main pole; and
providing a side shield, wherein the side gap is between the pole and the side shield, wherein the side shield has a gradient in a saturation magnetization such that the saturation magnetization changes in a yoke direction perpendicular to the WS, wherein the providing the side shield further includes:
providing a nonmagnetic structure having a side surface parallel to the WS;
providing at least one side shield layer, wherein a portion of the at least one side shield layer resides on the side surface, wherein the portion of the at least one side shield layer has the gradient in the saturation magnetization, and wherein at least part of the side shield is formed by the portion of the at least one side shield layer.

2. The method of claim 1 wherein the providing the at least one side shield layer includes conformally depositing the at least one side shield layer.

3. The method of claim 1 wherein the providing the side shield further includes:
depositing a seed layer before the providing the nonmagnetic structure.

4. The method of claim 3 wherein the depositing the at least one side shield layer further includes:
plating the at least side shield layer on the seed layer and the nonmagnetic structure.

5. The method of claim 4 wherein the plating the at least one side shield layer further includes:
plating a layer having a varying concentration of at least one magnetic material to provide the gradient in the saturation magnetization.

6. The method of claim 5 wherein the plating the layer occurs in a single plating cell.

7. The method of claim 1 wherein the at least one side shield layer includes a plurality of side shield layers, each of the plurality of side shield layers having a different saturation magnetization than another layer of the plurality of side shield layers.

8. The method of claim 1 wherein the gradient in the saturation magnetization is configured such that the saturation magnetization increases monotonically in the yoke direction.

9. The method of claim 1 wherein the nonmagnetic structure includes a top surface, an additional portion of the at least one side shield layer residing on the top surface, the providing the side shield further including:
depositing at least one nonmagnetic insulating layer; and
planarizing the at least one side shield layer and the at least one nonmagnetic insulating layer.

10. The method of claim 1 wherein the nonmagnetic structure is formed of a nonmagnetic metal.

11. The method of claim 10 wherein the nonmagnetic metal includes at least one of NiP, Cu, Ru, and NiCr.

12. The method of claim 1 wherein the providing the side gap includes:
removing a first portion of the at least one side shield layer to form a trench therein, a second portion of the at least one side shield layer forming the side shield; and
depositing at least one side gap layer, a portion of the at least one side gap layer residing in the trench.

13. The method of claim 12 wherein the providing the pole further includes:
depositing at least one pole material, a first portion of the at least one pole;
material residing in the trench and forming the pole; and
removing a second portion of the at least one pole material external to the trench.

14. The method of claim 13 wherein a third portion of the at least one side shield material in the trench below the pole forms a leading shield.

15. The method of claim 1 further comprising:
providing a leading shield; and
providing a trailing shield such that the leading shield, the trailing shield and the side shield form a wraparound shield.

16. The method of claim 1 wherein the saturation magnetization increases with increasing distance from the ABS.

17. The method of claim 1 wherein the saturation magnetization decreases with increasing distance from the pole in a cross-track direction.

18. A method for providing a data storage device having an air-bearing surface (ABS) comprising:
depositing a seed layer;
providing a nonmagnetic metal structure on the seed layer, wherein the nonmagnetic metal structure has a side surface parallel to the ABS and a top surface;
removing an uncovered portion of the seed layer exposed by the nonmagnetic metal structure;
providing a mask covering a portion of the top surface of the nonmagnetic metal structure;
conformally depositing at least one side shield layer, wherein a first portion of the at least one side shield layer resides on the side surface, wherein the first portion of the at least one side shield layer has a gradient in the saturation magnetization such that the saturation magnetization changes in a yoke direction perpendicular to the ABS, wherein a second portion of the at least one side shield layer resides on a remaining portion of the top surface not covered by the mask;
removing the mask;
depositing at least one nonmagnetic insulating layer after the mask is removed, wherein the at least one nonmagnetic insulating layer covers at least the at least one side shield layer and the portion of the nonmagnetic metal structure;
planarizing the at least one side shield layer and the at least one nonmagnetic insulating layer such that the nonmagnetic metal structure is exposed;
removing a first portion of the at least one side shield layer and the nonmagnetic metal structure to form a trench therein, wherein a second portion of the at least one side shield layer forms a side shield;
depositing at least one side gap layer, wherein a first portion of the at least one side gap layer resides in the trench, and wherein a second portion of the at least one side gap layer resides external to the trench;
depositing at least one pole material, wherein a first portion of the at least one pole material resides in the trench and forming the pole;
removing a second portion of the at least one pole material external to the trench and a second portion of the at least one side gap material, wherein the first portion of the at least one pole material forms the pole, wherein the first portion of the at least one side gap layer forms the side gap, and wherein a third portion of the at least one side shield layer below the pole forms a leading shield;
providing a write gap on a top of at least part of the pole; and
providing at least one coil for energizing the pole.

19. The method of claim 18 further comprising:
providing a trailing shield such that the leading shield, the trailing shield and the side shield form a wraparound shield.