Method for providing a side shield for a magnetic recording transducer using an air bridge

A method fabricates a side shield for a magnetic transducer having a nonmagnetic layer and an ABS location corresponding to an ABS. The nonmagnetic layer has a pole trench therein. The pole trench has a shape and location corresponding to the pole. A wet etchable layer is deposited. Part of the wet etchable layer resides in the pole trench. A pole is formed. The pole has a bottom and a top wider than the bottom in the pole tip region. Part of the pole in the pole tip region is in the pole trench on at least part of the wet etchable layer. At least parts of the wet etchable layer and the nonmagnetic layer are removed, forming an air bridge. The air bridge is between part of the pole at the ABS location and an underlying layer. Side shield layer(s) that substantially fill the air bridge are deposited.

BACKGROUND

FIG. 1is a flow chart depicting a conventional method10for fabricating for a conventional magnetic recording transducer including side shields. For simplicity, some steps are omitted. Prior to the conventional method10starting, underlayers such as a leading edge shield may be formed. The conventional method10typically starts by providing a pole, such as a perpendicular magnetic recording (PMR) pole, via step12. Step12includes fabricating the pole in a nonmagnetic layer, such as aluminum oxide. For example, a damascene process that forms a trench in the aluminum oxide layer, deposits nonmagnetic side gap/seed layers, and deposits magnetic pole layers may be used. In addition, the portion of the magnetic material external to the trench may be removed, for example using a chemical mechanical planarization (CMP) process.

The exposed aluminum oxide is wet etched, via step14. Thus, a trench is formed around a portion of the pole near the ABS location. Note that side gap layers may remain after the aluminum oxide etch in step14. The removal of the aluminum oxide in step14exposes the top surface of the leading edge shield. The side shields are deposited, via step16. Step16may include depositing seed layers and plating the side shields. Processing may then be completed, via step18. For example, a trailing edge shield and gap may be formed.

FIG. 2depicts plan and air-bearing surface (ABS) views of a portion of a conventional transducer50formed using the conventional method10. The conventional transducer50includes a leading edge shield52, side shield54, Ru side gap layer56which is deposited in the trench, a pole58, top gap layer60, and trailing shield62. Thus, using the conventional method10, the pole58, side shields54, and trailing shield62may be formed.

Although the conventional method10may provide the conventional transducer50, there may be drawbacks. The performance of the conventional transducer50may be compromised. In particular, fabrication using the method10may result in an interface53between the leading shield52and the side shields54. The side shield54thus has corners at which field may nucleate. As a result of the side shield corner fields, the media (not shown) may undergo unexpected erasures. Further, the interface53may be rough, not sufficiently clean, or otherwise less than ideal due to the wet etch performed in step14. There may also be other layers, including seed layer(s) between the leading shield52and the side shield54. These additional layers may further degrade performance of the side shield54.

Accordingly, what is needed is an improved method for fabricating a transducer.

SUMMARY

A method fabricates a side shield for a magnetic transducer. The magnetic transducer has a nonmagnetic layer and an air-bearing surface location (ABS location) corresponding to an air-bearing surface (ABS). The nonmagnetic layer has a pole trench therein. The pole trench has a shape and location corresponding to the pole. A wet etchable layer is deposited. A portion of the wet etchable layer resides in the pole trench. A pole having a pole tip region is formed. The pole has a bottom and a top wider than the bottom in the pole tip region. A portion of the pole in the pole tip region is in the pole trench on at least a first portion of the wet etchable layer. At least a second portion of the wet etchable layer and a portion of the nonmagnetic layer are removed such that an air bridge is formed. The air bridge is between the portion of the pole at the ABS location and an underlying layer. At least one side shield layer is deposited. A portion of the side shield layer(s) substantially fills the air bridge. In one aspect, the side shield layer(s) are interface-free between the pole and the underlying layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3is a flow chart depicting an exemplary embodiment of a method100for fabricating a transducer. The method100is may be used in fabricating transducers such as PMR or energy assisted magnetic recording (EAMR) transducers, though other transducers might be so fabricated. For simplicity, some steps may be omitted, performed in another order, and/or combined. The magnetic recording transducer being fabricated may be part of a merged head that also includes a read head (not shown) and resides on a slider (not shown) in a disk drive. The method100also may commence after formation of other portions of the PMR transducer. The method100is also described in the context of providing a single set of side shields and their associated structures in a single magnetic recording transducer. However, the method100may be used to fabricate multiple transducers at substantially the same time. The method100and system are also described in the context of particular layers. However, in some embodiments, such layers may include multiple sub-layers. In one embodiment, the method100commences after formation of the pole trench in a nonmagnetic intermediate layer. The pole trench has the shape and location of the pole to be formed. In some embodiments, the intermediate layer is an aluminum oxide layer. The nonmagnetic layer as well as the pole may reside on an underlayer. Further, in some embodiments, a leading edge shield is desired. In such embodiments, the leading edge shield may be considered part of the underlayer. The leading edge shield is generally ferromagnetic, magnetically soft, and may include materials such as NiFe. Further, an air-bearing surface location (ABS location) marks the surface at which the air-bearing surface (ABS) will reside. Finally, in some embodiments, the underlay(s) may be configured such that a bottom, or leading edge, bevel is formed.

At least one wet etchable layer is deposited after formation of the pole trench, via step102. Thus, a portion of the wet etchable layer(s) is in the pole trench. In some embodiments, step102includes providing a mask that has a front edge recessed from the ABS location. The front edge corresponds to the back edge of the wet etchable layer. The back edge of the wet etchable layer may be desired to be within twenty nanometers from the back edge the side shields. Thus, the front edge of the mask may be within twenty nanometers of the desired back edge of the side shields. In some embodiments, the back edge of the wet etchable layer is desired to be aligned as closely as possible to the back edge of the side shield. Thus, the front edge of the mask may be aligned to the desired back edge of the side shields. The mask thus has an aperture that extends at least from the ABS location to the front edge of the mask. In some embodiments, in which the pole is formed with an anchor structure opposite to the pole from the ABS location, the aperture extends to a portion of the anchor structure. Once the mask is in place, the wet etchable layer is deposited. In some embodiments, the wet etchable layer is aluminum oxide. Step102may then include depositing the aluminum oxide layer using atomic layer deposition (ALD). In other embodiments, other materials and/or other deposition methods may be used. After the wet etchable layer has been deposited, the mask may be removed. Although described as a wet etchable layer, the layer deposited in step102may be removed by another method as long as the layer may be completed removed in the space between the pole (described below) and the underlying layer(s).

A pole having a pole tip region is formed, via step104. Step104typically includes depositing seed and other layers as well as depositing high saturation magnetization materials for the pole. In some embodiments, step104includes plating the high saturation magnetization layers. Further, between steps102and104or as part of step104, one or more wet etch stop layer(s) may be provided. In some embodiments, seed, adhesion, or other layers may be deposited as part of formation of the wet etch stop layer(s). In some embodiments, the pole has a bottom and a top wider than the bottom in the pole tip region. A portion of the pole in the pole tip region is in the pole trench and on at least a first portion of the wet etchable layer.

At least part of the wet etchable layer is removed, via step106. In addition, a portion of the nonmagnetic layer adjacent to the sidewalls of the pole is also removed. In some embodiments, the wet etchable layer and nonmagnetic intermediate layer in which the pole trench is formed are the same material: aluminum oxide. In such embodiments, a single wet etch may remove the desired parts of both layers. However, in other embodiments, multiple wet etches including wet etches using different etch chemistries may be used. Further, other processes that are appropriate might also be used. Because some or all of the wet etchable layer is removed, an air bridge is formed between the portion of the pole in the pole tip region at the ABS location and an underlying layer, via step106. The air bridge occupies the space under the pole in which the wet etchable layer had resided. In some embodiments, the wet etch performed in step106may also remove a portion of the underlying layer(s). Thus, the air bridge formed in step106may have a thickness of not more than one micron. In other embodiments, the air bridge may be only as thick as the wet etchable layer.

FIGS. 4A-4Bdepict a magnetic transducer150during formation using the method100. In particular, side and ABS views are shown inFIGS. 4A and 4B, respectively. For clarity,FIGS. 4A-4Bis not to scale. The magnetic transducer150may be part of a merged heat that includes at least one read transducer (not shown) in addition to at least one magnetic transducer150. The magnetic transducer150includes an underlayer152, and a bottom, or leading edge shield154. In some embodiments, the leading edge shield154may be considered to be an underlayer. The leading edge shield154may also be omitted. The leading edge shield154is also shown as including a beveled surface155that corresponds to the bevel to be formed in the pole. Also shown are nonmagnetic layers158and162. These layers are etch stop layers158and162. Each etch stop layer158and162may include multiple sublayers. The etch stop layer158is shown as connecting to layer152. In some embodiments, the layer152and158are formed of the same material, such as Ru. Thus, a dotted line is shown between the two layers152and158. The pole160has also been formed. In the embodiment shown, the pole160includes a bevel corresponding to the beveled surface155. However, in other embodiments, the pole160may not have a leading edge bevel. The wet etch stop layers158and162substantially surround the pole160in the pole tip region. Thus, the pole160may be protected from the etchant used in the wet etch step106of the method100.

In addition, an air bridge156has been formed. The air bridge156exists between the bottom of the pole160and the underlying layers152and154. In some embodiments, the wet etch of step106may also remove portions of the underlayer(s)152and154. In such embodiments, the air bridge156may have a thickness of up to a micron. In other embodiments, the air bridge156may have a different thickness. Although not shown, the pole160may have an anchor portion (not shown inFIG. 4A) on the opposite side of the ABS location as the remainder of the pole (e.g. on the left ofFIG. 4A). Thus, although shown inFIG. 4Aas being supported only at the right (e.g. the yoke) region, the pole160may be supported on both sides of the air bridge156. Further, the nonmagnetic layer (not shown) in proximity to the sides of the pole160have been removed. Thus, the pole160and wet etch stop layer158and162appear to be floating in the ABS view ofFIG. 4B.

Referring back toFIG. 3, the material(s) for the side shield are deposited, via step108. In some embodiments, step108includes depositing seed layer(s). The soft magnetic material(s) for the side shield may be plated in step108. These materials fill the region around the pole160. Thus, the air bridge156is substantially filled as is the region adjacent to the sidewalls. In some embodiments, a full wrap around shield is plated in step108. The back of the side shields fabricated in step108may be within twenty nanometers of the back of the air bridge156. Fabrication of the transducer150may then be completed. For example, a portion of the pole160near the ABS may be removed to form a trailing edge bevel. A top, or trailing edge, shield may also be formed. Other components including but not limited to coil(s), a write gap, and a top shield may be formed.

FIGS. 5A-5Bdepict a magnetic transducer150during after formation is continued using the method100. In particular, side and ABS views are shown inFIGS. 5A and 5B, respectively. For clarity,FIGS. 5A-5Bare not to scale. The magnetic transducer150is shown after step110is performed. Thus, the side shield164has been fabricated. As can be seen inFIG. 5B, the side shield is continuous from the one side of the pole160, to below the pole160and then to the opposite side of the pole160.

Using the method100, side shield164having the desired geometry may be fabricated. More specifically, the side shield164is continuous. Thus, the side shield164may be viewed as not having corners near the pole160. Similarly, the interface between the leading shield154and the side shield164adjacent to the pole160has been removed. Thus, nucleation of fields due to corners of the side shield164may be reduced. Further, any interface between the side shield164and the lead shield layer154may be moved further from the pole160and improved in quality. Thus, performance of the transducer150may be improved.

FIG. 6is a flow chart depicting another exemplary embodiment of a method200for fabricating a transducer using an air bridge. For simplicity, some steps may be omitted. FIGS.7A-7C-FIGS. 18A-18Care diagrams depicting side, ABS location and plan views of an exemplary embodiment of a portion of a transducer during 250 fabrication. For clarity, FIGS.7A-7C-FIGS. 18A-18Care not to scale. Although FIGS.7A-7C-FIGS. 18A-18Cdepict the ABS location (location at which the ABS is to be formed) and ABS at a particular point in the pole, other embodiments may have other locations for the ABS. Referring toFIGS. 6-18C, the method200is described in the context of the transducer250. However, the method200may be used to form another device (not shown). The transducer250being fabricated may be part of a merged head that also includes a read head (not shown in FIGS.7A-7C-FIGS. 18A-18C) and resides on a slider (not shown) in a disk drive. The method200also may commence after formation of other portions of the transducer250. The method200is also described in the context of providing a single transducer250. However, the method200may be used to fabricate multiple transducers at substantially the same time. The method200and device250are also described in the context of particular layers. However, in some embodiments, such layers may include multiple sublayers.

A leading edge magnetic shield layer is deposited, via step202. In some embodiments, step202includes depositing a NiFe shield layer on one or more other underlayers. In some embodiments, these underlayers include an alumina underlayer and at least one nonmagnetic layer on the alumina underlayer. In some embodiments, the nonmagnetic layer includes Ru. In some such embodiments, a Ti adhesion layer may be provided between the alumina underlayer and the leading shield layer. In embodiments in which a leading shield is omitted, step202may be skipped.

A beveled surface may be formed in the leading shield layer, via step204. The beveled surface is formed by removing a portion of the leading edge magnetic shield layer distal from the ABS in step204. Step204may include forming a hard mask in a region near the ABS location. In some embodiments, the hard mask resides on the leading shield layer at a location on the opposite side of the ABS location as the side at which the pole is developed. In some embodiments, the hard mask includes a trilayer of Ta/Ru/Ta that may also function as a stop layer. The hard mask may be formed by depositing the hard mask layers, forming a photoresist mask on the hard mask layers, and removing the exposed portion of the hard mask layers. The leading shield layer may then be removed to form the beveled surface, for example by ion milling at a nonzero angle from normal to the surface of the leading shield.FIGS. 7A-7Cdepict side, ABS and plan views of the transducer250after step204is performed. Thus, underlayers251,252, and253are shown. Also depicted is leading shield layer254having beveled surface255. The hard mask256used is also shown.

A nonmagnetic intermediate layer having a top surface substantially perpendicular to the ABS location is provided, via step206. In some embodiments, step206includes multiple substeps. For example, a nonmagnetic intermediate layer, such as aluminum oxide may be deposited. However, the deposition process may be conformal to the beveled surface255. Thus, the top surface of the alumina may not be perpendicular to the ABS location (e.g. flat). A planarization such as a CMP may then be carried out and the hard mask156removed. Thus, the top surface of the intermediate layer and the leading shield layer254may be aligned. Another aluminum oxide layer may then be deposited. The two aluminum oxide layers may be considered to form a single, nonmagnetic intermediate layer.FIGS. 8A-8Cdepict side, ABS location, and plan views of the transducer250after step206is completed. Thus, intermediate layer258is shown. In some embodiments, the layer25iis alumina and includes sublayers (not separately shown).

A pole trench is formed in the intermediate layer258, via step208. Step208may include depositing hard mask layer(s) and providing a photoresist mask on the hard mask layers. The photoresist mask includes an aperture having a location and width corresponding to the desired trench. The underlying hard mask may then be etched, forming an aperture in the hard mask. The intermediate layer may then be etched in the region under the aperture in the hard mask. Thus, a pole trench having a bottom, a top wider than the bottom, and a location corresponding to a pole is formed. A portion of the bottom of the pole trench in a pole tip region proximate to the ABS location being formed by the beveled surface of the leading edge magnetic shield layer.FIGS. 9A-9Cdepict the transducer after step210is performed. Thus, trench262is shown.

A mask having a front edge and covering a portion of the pole trench distal from the ABS location is provided, via step210. The front edge of the mask is not more than 20 nm from a desired back edge of a full wrap around shield. FIGS.10A-10C depict the transducer250after step210is performed. Thus, mask264is shown. The mask264covers a portion of the trench262.

At least one wet etchable layer is deposited, via step212. Step212may include depositing an aluminum oxide layer. In some embodiments, step212is performed using ALD. In some embodiments, step212includes deposition of a an adhesion layer.FIGS. 11A-11Cdepict side, ABS, and plan views of the transducer250after step212is performed. Thus, alumina layer266is shown. In some embodiments, a portion of the aluminum oxide layer266in the pole trench. Also shown is Ti adhesion layer267that may also be deposited. In other embodiments, Ti layer267may be omitted. Note that the location of the trench262is shown by a dotted line inFIG. 11C.

The mask264is removed, via step214. At least one wet etch stop layer is also deposited, via step216. In some embodiments, step216includes performing a CVD Ru deposition.FIGS. 12A-12Cdepict the transducer250after step214is performed. Thus, Ru layer268has been formed.

At least one pole material is deposited on the at least one wet etch stop layer, via step218. The trench264is thus filled.FIGS. 13A-13Cdepicts side, ABS, and plan views of the transducer after step218is performed. Thus, material(s)270for the pole are shown.

The transducer is planarized, via step220. Thus, a portion of the pole material(s)270shown is removed.FIGS. 14A-14Cdepicts side, ABS, and plan views of the transducer250after step220is performed. Thus, portions of the pole material270external to the trench are removed and a pole270′ is formed. The pole270′ has a plurality of sidewalls, a pole bottom, a pole top, and a pole tip portion. A portion of the pole270′ also resides in the pole tip region of the pole trench. The pole tip portion of the pole270′ residing on at least a first portion of the Ru etch stop layer268. As can be seen inFIG. 14B, the pole top is wider than the pole bottom in at least the pole tip portion.

At least an additional wet etch stop layer is deposited, via step222. In some embodiments, step222includes providing a mask having an aperture over the pole and then depositing the wet etch stop layer(s).FIGS. 15A-15Cdepict side, ABS, can plan views of the transducer250after step222is performed. In the embodiment shown, two layers272and274are shown. These layers272and274cover the top of the pole270′ and a portion of the wet etch stop layer268in the pole tip region. In the embodiment shown, a Ti adhesion layer272is also shown. However, in other embodiments, other materials may be used or the layer272may be omitted. Also shown is mask273that may be used in forming the additional wet etch layer274. As can be seen inFIG. 15B, a combination of the wet etch stop layer(s)268and274substantially surround the sidewalls, the bottom, and the pole top in the pole tip region.

The aluminum oxide layer266and a second portion of the intermediate layer258are wet etched, via step224. Thus, an air bridge is formed.FIGS. 16A-16Ddepict side, ABS, yoke, and plan views of the transducer250after step224is performed. An air bridge276is shown. The air bridge276is between at least the leading edge magnetic shield layer254and the wet etch stop layer268on which bottom of the pole tip portion of the pole270′ resides. Note, however, that the air bridge276extends only under a portion of the pole270′. This may best be seen inFIG. 16A(side view) and a comparison ofFIG. 16B(ABS view) and16C (view closer to the yoke).

A full wrap around side shield is plated, via step226.FIGS. 17A-17Cdepicts side, ABS, and plan views of the transducer after step26is performed. Thus, a wraparound side shield278is shown. A portion of the full wrap around side shield275substantially fills the air bridge. In some embodiments, a trailing edge bevel may be formed, via step228. Step228may include performing a planarization such as a CMP and removing a portion of the pole260′. This removal may be accomplished by providing a mask covering a portion of the pole270′ distal from the ABS location and performing an ion mill. A top shield may then be plated, via step230.FIGS. 18A-18Bdepict side and ABS views of the transducer250after step230is performed. Thus, a trailing edge bevel280, gap layer282and top shield284are shown.

Thus, using the method200, the transducer250may be fabricated. The transducer250shares the benefits of the transducer150. A side shield278that is continuous and interface free below the pole278may be formed. Thus, performance of the transducer250may be improved.