Magnetic write pole having engineered radius of curvature and chisel angle profiles

Description

BACKGROUND

FIGS. 1A and 1B depict air-bearing surface (ABS) and plan views of a conventional magnetic recording head 10. The magnetic recording transducer 10 may be a perpendicular magnetic recording (PMR) head. The conventional magnetic recording transducer 10 may be a part of a merged head including the write transducer 10 and a read transducer (not shown). Alternatively, the magnetic recording head may be a write head including only the write transducer 10. The conventional transducer 10 includes an underlayer 12 that may include a leading shield, side gap 14, side shields 16, top (write) gap 17, optional top shield 18 and main pole 20.

The side shields 16 are separated from the main pole 20 by a side gap 14. The side shields 16 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.

The main pole 20 resides on an underlayer 12 and includes sidewalls 22 and 24. The underlayer 12 may include a leading shield. The sidewalls 22 and 24 of the conventional main pole 20 form an angle with the down track direction at the ABS. Thus, the top of the main pole 20 is wider than its bottom. In addition, sidewalls of the pole tip forms a chisel angle with the yoke direction (i.e. perpendicular to the ABS) at and near the ABS. Typically, the chisel angle is constant at and near the ABS.

Although the transducer 10 functions, performance of the transducer 10 may suffer at higher recording densities. For example, in the range of close to or above one Tb/in², the main pole 20 is scaled down in size. In this size range, the reduction in the physical geometry of the main pole 20 may result in a loss in write field. Further, reverse overwrite may also suffer. Thus, performance of the conventional transducer 10 may suffer at higher recording densities.

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 an exemplary embodiment of a magnetic recording disk drive and transducer.

FIGS. 3A and 3B depict radius of curvature and chisel angle versus distance from the ABS in one embodiment of a magnetic recording transducer.

FIGS. 4A and 4B depict radius of curvature and chisel angle versus distance from the ABS in one embodiment of a magnetic recording transducer.

FIGS. 5A and 5B depict radius of curvature and chisel angle versus distance from the ABS in one embodiment of a magnetic recording transducer.

FIG. 6 depicts a flow chart of an exemplary embodiment of a method for providing a magnetic recording transducer.

FIG. 7 depicts a flow chart of another exemplary embodiment of a method for providing a magnetic recording transducer.

FIG. 8A-8B through 12A-12B depict various views of an exemplary embodiment of a mask and an exemplary embodiment of a magnetic recording transducer during fabrication using the mask.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 2A, 2B and 2C depict various views of an exemplary embodiment of a disk drive and transducer 100. FIG. 2A depicts a side view of the disk drive. FIGS. 2B and 2C depict ABS and plan views of portions 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 200 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 a 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, an intermediate layer (not shown in FIGS. 2B and 2C), a main pole 110, coil(s) 120, side shields 130 and trailing shield 140. The underlayer 106 may include a leading shield (LS) at and near the ABS. The coil(s) 120 are used to energize the main pole 110. One turn is depicted in FIG. 2A. Another number of turns may, however, be used. Typically, multiple turns are 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. Alternatively a helical may be used. Further, additional coils may also be used.

Also shown is a gap 108. In some embodiment, the side gap 108 also functions as a leading gap between a leading shield and the main pole 110 and a write gap between the main pole 110 and the trailing shield 140. In other embodiments, other layer(s) may form all or part of the leading gap and/or the write gap. In the embodiment shown in FIGS. 2B-2C, the side shields 130 are conformal in the region of the pole tip. However, in other embodiments, some portion of the side shields 130 may be nonconformal. In addition, the side shields 130, trailing shield 140 and leading shield 106 may be configured differently or omitted. For example, the shields 130, 140 and leading shield of underlayer 106 may form a wraparound shield. In other embodiments, the side shield 130 may be configured as a half shield which terminates between the top and bottom of the pole 110. In such embodiments, the trailing shield 140 may be used but the leading shield in the underlayer 106 omitted. In other embodiments, one or more of the leading shield, side shields 130 and trailing shield 140 may be omitted or configured differently.

The main pole 110 includes a yoke region and a pole tip that has an ABS-facing surface. The ABS-facing surface may reside at the ABS. Such an embodiment is depicted in FIGS. 2A-2C. In other embodiments, the ABS-facing surface may be recessed from the ABS. The pole tip is a region proximate to the ABS and is between the yoke and the ABS. In some embodiments, the pole tip extends not more than five hundred nanometers from the ABS in the yoke direction (perpendicular to the ABS). In other embodiments, the pole tip extends not more than four hundred fifty nanometers from the ABS. In some such embodiments, the pole tip extends not more than two hundred nanometers from the ABS in the yoke direction. In some embodiments, the pole tip may be considered to extend up to a location for which the chisel angle, discussed below, becomes constant. Behind the pole tip (e.g. in the yoke region), the chisel angle may is considered to be replaced by another quantity, such as a flare angle.

In FIG. 2B, the main pole 110 is shown as having a top wider than the bottom. The pole tip of the main pole 110 thus includes sidewalls having sidewall angles that are greater than or equal to zero with respect to the down track direction. In an embodiment, these sidewall angles differ at different distances from the ABS.

The sidewalls also from a chisel angle with the yoke direction, as can be seen in FIG. 2C. The chisel angle is the angle that a tangent to the sidewall forms with the yoke direction. For clarity, only two chisel angles, α₁ and α₂, for one sidewall are shown. The variations in the chisel angles for the two sidewalls of the main pole 110 may be substantially the same. Thus, the main pole 110 is symmetric. However, in other embodiments, the main pole 110 may not be symmetric. This lack of symmetry may be because of a design or due to fabrication.

Further, the sidewalls may also be characterized by a radius of curvature. The radius of curvature at a point along the sidewall is the radius of a circle having a curvature substantially matching that of the sidewall at that point and is perpendicular to the tangent to the sidewall at the point. Thus, as can be seen in FIG. 2C, the radius of curvature is perpendicular to the tangent that forms the chisel angle. For clarity, the radii of curvature are shown for only two points along a sidewall. Thus, one location has a chisel angle α₁ and a radius of curvature R₁ while the other location has a chisel angle α₂ and a radius of curvature R₂.

The pole tip is configured such that the chisel angle for the pole tip continuously increases in the yoke direction to a maximum a first distance from the ABS, while the radius of curvature for the pole tip has a minimum radius of curvature a second distance from the ABS in the yoke direction. The first distance is greater than the second distance. Stated differently, the maximum in the chisel angle occurs at a location further from the ABS than the location of the minimum in the radius of curvature. In some embodiments, the minimum of the radius of curvature may occur at the ABS-facing surface of the pole tip. The radius of curvature may change smoothly through the minimum in the radius of curvature. Similarly, the chisel angle may change smoothly through the maximum in the chisel angle. Thus, the chisel angle and/or radius of curvature may follow smooth curves

For example, in some embodiments, the chisel angle is at least ten degrees and not more than thirty degrees at the ABS-facing surface. In some such embodiments, the chisel angle is at least fifteen degrees and not more than twenty-five degrees at the ABS-facing surface. The chisel angle smoothly increases with distance from the ABS in the yoke direction to a maximum. In some embodiments, this maximum is greater than fifty degrees. In some embodiments, the maximum in the chisel angle occurs at least one hundred and not more than two hundred nanometers from the ABS-facing surface. In other embodiments, other distances are possible. In general, however, it is desirable for the minimum in the radius of curvature to occur closer to the ABS-facing surface (e.g. the ABS) than the maximum in the chisel angle. In some embodiments, the chisel angle smoothly decreases from the maximum as the distance from the ABS increases further. The chisel angle may then become constant some distance from the ABS. These changes in the chisel angle may also be smooth. In other words, over this region (the pole tip) the chisel angle follows a curve having no sharp corners. As discussed above, at some location greater than or equal to the distance from the ABS at which the chisel angle becomes constant, the pole tip may be considered to terminate.

In contrast to the chisel angle, the radius of curvature has a minimum some distance from the ABS-facing surface. In some embodiments, this distance is at least zero nanometers and not more than eighty nanometers. Thus, the minimum may occur at the closest portion of the main pole 110 to the ABS, including at the ABS. In other embodiments, the minimum is at least twenty nanometers from the ABS-facing surface. In some such embodiments, the minimum is a distance from the ABS-facing surface of at least forty nanometers and not more than sixty nanometers.

Thus, both the chisel angle and radius of curvature change smoothly through the pole tip. The minimum in the radius of curvature occurs at a location for which the chisel angle is increasing smoothly. Stated differently, the minimum in the radius of curvature is closer to the ABS than the maximum in the chisel angle. Comparisons of the radius of curvature and chisel angle may be seen in FIGS. 3A-5B. FIGS. 3A and 3B depict graphs 150 and 160, respectively, of the radius of curvature and chisel angle versus distance from the ABS. FIGS. 3A and 3B are not to scale and may have different scales for horizontal and/or vertical axes. In a main pole 110 corresponding to the graphs 150 and 160, the ABS-facing surface of the main pole 110 is at the ABS. As can be seen in FIGS. 3A and 3B, the radius of curvature changes smoothly through the minimum. As can be seen in FIG. 3A, the radius of curvature decreases continuously (e.g. with no increase) to the minimum and increases continuously further from the ABS than the minimum. Stated differently, the radius of curvature monotonically decreases, then monotonically increases. However, for other embodiments, the slope and shape of the curve may differ. For example, if the minimum in the radius of curvature is at the ABS/ABS-facing surface, then the radius of curvature will simply smoothly and monotonically increase. Similarly, the chisel angle changes smoothly through the maximum and through the constant chisel angle further from the ABS. As can be seen from the graph 160, the chisel angle increases continuously through the maximum, then decreases smoothly further from the ABS. The chisel angle becomes constant further from the ABS, at or near termination of the pole tip. Thus, the chisel angle monotonically increases, then monotonically decreases, and then becomes constant.

Although particular curves are depicted in FIGS. 3A and 3B, the radius of curvature and chisel angle are not limited to this dependence. For example, FIGS. 4A and 4B depict graphs 150′ and 160′ of radius of curvature and chisel angle for another embodiment of the main pole 110. FIGS. 4A and 4B are not to scale and may have different scales for horizontal and/or vertical axes. Although shaped differently, the general trends are the same as for the graphs 150 and 160. For example, the radius of curvature in graph 150′ and chisel angle in graph 160′ vary smoothly with distance from the ABS-facing surface (here, the ABS). The radius of curvature monotonically decreases, then monotonically increases in graph 150′. Thus, the chisel angle of graph 160′ monotonically increases, then monotonically decreases, and then becomes constant. Further, the minimum in the radius of curvature is closer to the ABS than the maximum in the chisel angle.

FIGS. 5A and 5B depict graphs 150″ and 160″ of radius of curvature and chisel angle for still another embodiment of the main pole 110. FIGS. 5A and 5B are not to scale and may have different scales for horizontal and/or vertical axes. Although shaped differently, the general trends are the same as for the graphs 150 and 160. For example, the radius of curvature in graph 150″ and chisel angle in graph 160′ vary smoothly with distance from the ABS-facing surface (here, the ABS). The radius of curvature monotonically decreases, then monotonically increases in graph 150″. Thus, the chisel angle of graph 160″ monotonically increases, then monotonically decreases, and then becomes constant. Further, the minimum in the radius of curvature is closer to the ABS than the maximum in the chisel angle.

The magnetic transducer 100 may have improved performance, particularly at higher recording densities. The desired profile of the pole 110, particularly the radius of curvature and chisel angle discussed above, may increase the effective magnetic volume of the pole 110 near the ABS. For example, a small radius of curvature corresponds to a more rapid increase in volume of magnetic material. This increase in volume results in a higher magnetic field due to the main pole 110. This increase may cause an increase in the write field magnitude and gradient. Thus, writability of the main pole 110 may be enhanced. In addition, other aspects of performance, such as the error margin may be improved. Other issues, such as adjacent track interference and wide area track erasure, may be comparable. Thus, overall performance of the transducer 100 may be improved.

FIG. 6 depicts an exemplary embodiment of a method 200 for providing a magnetic recording transducer. For simplicity, some steps may be omitted, interleaved, combined and/or performed in another order. The method 200 is described in the context of providing a single magnetic recording disk drive and transducer 100. However, the method 200 may be used to fabricate multiple magnetic recording transducers at substantially the same time and may be used to fabricate other transducers. 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 head. For example, the method 200 may start after a read transducer, return pole/shield and/or other structure have been fabricated. In addition, an intermediate layer, such as an aluminum oxide layer, in which the pole is formed has been fabricated.

The main pole 110 is provided, via step 202. Step 202 may include forming a trench in one or more layers that corresponds to the pole footprint (e.g. the plan view). For example, a photoresist mask having the desired shape may be provided on an intermediate layer. Hard mask layer(s) may be deposited on the photoresist mask and the photoresist mask removed. The hard mask so formed has an aperture having a shape corresponding to the photoresist mask. An etch or other removal process may then be performed in order to form the trench corresponding to the main pole. The trench formed has the desired geometry and location for formation of the main pole. For example, the top of the trench may be wider than the bottom so that the top of the main pole may be wider than the bottom. If a leading edge bevel is desired, the bottom of the trench may slope in the yoke direction. The trench may also be narrower in the pole tip region, near the ABS, than in the yoke region recessed from the ABS. The sidewalls of the trench may also be provided such that the desired radius of curvature and chisel angle may be provided. After formation of other structures, such as a bottom or side gap, the formation of the main pole 110 may be completed by deposition of magnetic pole materials and, in some embodiments, a planarization or other process that removes any excess pole materials. In some embodiments, this portion of step 202 includes plating or otherwise depositing high saturation magnetization magnetic material(s). Further, a top, or trailing, bevel may be formed in the main pole 110. Formation of the trailing bevel may include covering a portion of the main pole recessed from the ABS and then ion milling the main pole at an angle from the down track direction. This step may be performed after or interleaved with formation of the side shields. The trench may also have been configured in step 202 such that the depth varies in the pole tip region. Thus, the main pole may also have a bottom, or leading, bevel.

The bottom, side and/or write gap(s) are provided, via step 204. Step 204 may include depositing one or more nonmagnetic layers such that the bottom and side gaps are formed in the trench. If a nonconformal side gap is desired, additional masking and/or deposition steps may also be performed. At least part of step 204 may also be performed before deposition of the pole material(s) in step 202. However, formation of the write gap is carried out after the pole materials have been provided.

The shield(s) 106, 130 and/or 140 are optionally provided, via step 206. Step 206 may include covering a portion of the transducer with a mask, removing some portion(s) of the intermediate layer and plating or otherwise providing the material(s) for the side shields. In some embodiments, the side shields 130 may be formed before the main pole 110 is formed.

The coils 120 may also be formed, via step 208. Step 208 includes multiple masking and deposition steps that may be performed before and/or after the steps 202, 204 and 206. For example, if the coil 120 is a spiral coil, then step 208 may be completed before the steps 202, 204 and 206. In other embodiments, the coil 120 may be a toroidal (helical) coil, some of which is formed before the main pole 120 and some of which may be formed after the main pole 110.

Using the method 200, a magnetic transducer having improved performance may be fabricated. In particular, the magnetic field magnitude, gradient in the magnetic field and other properties may be enhanced. Thus, fabrication and performance of the transducer may be improved.

FIG. 7 depicts an exemplary embodiment of a method 210 for providing a main pole 110 in a magnetic recording transducer. For simplicity, some steps may be omitted, interleaved, and/or combined. FIGS. 8A-8B through 12A-12C depict various views of a mask 250 and a transducer 260 during fabrication using the method 210. For clarity, FIGS. 8A-12C are not to scale. For simplicity not all portions of the disk drive and transducer 260 are shown. In addition, although the disk drive and transducer 260 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 including the transducer 260 may be a PMR disk drive. However, in other embodiments, the disk drive may be configured for other types of magnetic recording included but not limited to HAMR.

The method 210 is described in the context of providing a magnetic recording disk drive and transducer 260. However, the method 210 may be used to fabricate multiple magnetic recording transducers at substantially the same time. The method 210 may also be used to fabricate other magnetic recording transducers. 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 head. For example, the method 210 may start after a read transducer, return pole/shield and/or other structure have been fabricated. The method 210 may also start after an intermediate layer, such as silicon oxide and/or aluminum oxide has been provided. Thus, the intermediate layer may be nonmagnetic and may include multiple constituents.

A photoresist layer is provided on the intermediate layer, via step 212. The photoresist layer may be spin coated on the intermediate layer or provided in another manner.

The photoresist layer is exposed to light using a mask having a shape corresponding to the pole tip, via step 214. The shape of the mask includes a spacer therein. The spacer covers a region corresponding to the minimum in the radius of curvature of the main pole being formed. The exposure may also be performed using off-axis illumination. For example, in some embodiments, quadrupole illumination may be used. A portion of the photoresist layer is removed, via step 216. Step 216 may include using a developer to remove the exposed portions of the photoresist layer. FIG. 8A depicts the mask 250 used in step 214. FIG. 8B is a plan view of the transducer 260 after step 216 is performed. The mask 250 used in illuminating the photoresist layer includes sections 254 and 256 having a spacer 252 between the two sections. The intermediate layer 262 and photoresist mask 264 formed using the mask 250 are shown in FIG. 8B. The minimum in radius of curvature occurs within region 265. The region 265 in the photoresist mask 264 corresponds to the spacer 252. This region 265 includes the location at which the radius of curvature is a minimum for the pole being formed.

One or more hard mask layers are deposited, via step 218. FIG. 9 depicts a plan view of the transducer 260 after step 218 has been performed. Thus, a hard mask layer 266 is shown. The location of the photoresist mask 264 is indicated by dashed lines in FIG. 9.

The photoresist mask 264 is removed, via step 220. Step 220 may include using a lift-off process. FIG. 10 depicts a plan view of the transducer 260 after step 220 has been completed. The photoresist mask 264 and portion of the hardmask layer(s) 266 on the photoresist mask 264 have been removed. Thus, a hard mask 266′ remains. The hard mask 266′ includes a region 267 that corresponds to the spacer 252 in the mask 250 depicted in FIG. 8A. Referring back to FIG. 10, the underlying intermediate layer 262 is exposed by the hard mask 266′. This exposed portion of the intermediate layer 262 has substantially the same shape and location as the photoresist mask 264.

A portion of the intermediate layer 262 is removed, via step 222. A trench for the main pole is thus formed. Step 222 may include performing one or more reactive ion etches (RIEs). In some embodiments, the RIE(s) and/or the intermediate layer 254 are configured such that the trench has different sidewall angles in different portions of the pole. For example, the sidewall angles at and near the ABS may be larger (further from perpendicular to the surface of the intermediate layer) than the sidewall angles in regions recessed from the ABS (termed the yoke herein). FIGS. 11A and 11B depict plan and ABS location views of the transducer 260 after the trench has been provided by removal of the intermediate layer 262 under the aperture in the hard mask 266′. Thus, a trench 268 has been formed. The trench may expose the underlying topology. For example, the underlayer/leading shield 261 may be exposed. In other embodiments, the bottom of the trench may be in the intermediate layer 262. The trench 268 has a top wider than the bottom at the ABS and a shape corresponding to the pole.

The main pole is provided, via step 224. High saturation magnetization magnetic material(s) may thus be provided by plating and/or other means. In addition, other portions of the pole may be formed using other material(s). The main pole material(s) may also be planarized. A trailing bevel may also be formed. FIGS. 12A and 12B depict plans and ABS views of the transducer 260 after step 224 has been performed. Although not indicated in the method 210, a gap 269 has also been formed. The pole 270 is also present. The main pole 270 has a top wider than the bottom at least in the pole tip. The radius of curvature and chisel angle are also configured as discussed above for the main pole 110. The main pole 270 thus has a region 271 in which the minimum of the radius of curvature occurs. This region 271 corresponds to the spacer 252 in the mask 250. Fabrication of the transducer 260 may be completed.

Using the method 210, a magnetic transducer 260 having improved performance may be fabricated. In particular, use of the mask 250 in illuminating/exposing the photoresist layer results in the desired profile of the photoresist mask 262. This allows the main pole 270 to have the desired shape, particularly for the chisel angle and radius of curvature of the main pole. The magnetic field magnitude, gradient in the magnetic field and other properties for the main pole 270 may thus be improved. Thus, performance of the transducer may be enhanced.