Write gap structure for a magnetic recording head

The present application relates to a write gap structure for a magnetic recording head. In illustrated embodiments, the write gap structure includes multiple write gap segments along a beveled pole tip surface between a top edge and a bottom edge of the beveled pole tip surface to provide a narrow write gap proximate to the air bearing surface and a larger write gap behind the air bearing surface. In illustrated embodiments, the narrow write gap segment is formed between the beveled pole tip surface and a lower back surface of front shield and the larger write gap is formed between the beveled pole tip surface and an upper back surface of the front shield.

BACKGROUND

Data storage devices use magnetic recording heads to read and/or write data on a magnetic storage media, such as a rotating disc. Magnetic recording heads typically include inductive write elements to record data on the storage media. Inductive write elements include a main pole and pole tip and one or more return poles. Current is supplied to write coils to induce a flux path in the main pole to record data on one or more magnetic storage layers of the media. Data can be recorded using parallel and perpendicular recording techniques. Demand for increased storage has created demand for higher field gradients to record more data in smaller spaces. Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.

SUMMARY

The present application relates to a write gap structure for a magnetic recording head. As disclosed, the write gap structure has a narrow write gap width, for example, less than 25 nanometers (nm), between the write pole and a front shield proximate to an air bearing surface to enhance field gradient for higher density recording. In particular, in illustrated embodiments disclosed, the narrow write gap width provided at the air bearing surface is 20 nm or less

In embodiments disclosed, the write gap structure includes multiple write gap segments along a beveled pole tip surface between a top edge and bottom edge of the beveled pole tip surface. The multiple write gap segments include a proximal write gap segment located proximate to the air bearing surface and a distal gap segment recessed from the air bearing surface behind the proximal gap segment. In illustrated embodiments, the proximal write gap segment extends between the beveled pole tip surface and a lower front surface of the front shield to provide the narrow gap width proximate to the air bearing surface. The distal gap segment, has a larger gap width than the narrower gap width and extends between the beveled surface and an upper front surface of the front shield.

In illustrated embodiments, the upper front surface of the front shield is spaced forward from the lower front surface in a direction away from the beveled pole tip surface to provide the larger write gap width of the distal write gap segment. The upper front surface is connected to the lower front surface via a step. In another embodiment, the upper front surface has a different incline angle than the lower front surface to provide the larger write gap width of the distal write gap segment. For example, in one illustrated embodiment, the lower front surface is inclined at an angle conformal to the slope angle of the beveled pole tip surface and the upper front surface is inclined at a non-conformal angle with respect to the beveled pole tip surface of the pole tip to provide the larger write gap width.

The application discloses process steps including deposition of multiple layers and selective etching to form the multiple write gap segments and upper and lower front surfaces of the front shield as described. Other features and benefits that characterize embodiments of the present invention will be apparent upon reading the following detailed description and review of the associated drawings.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The present application relates to a write assembly for a magnetic recording head for data storage devices100of the type illustrated inFIG. 1. As shown inFIG. 1, the data storage device100includes a magnetic data storage media or disc102and head104. The head104including one or more transducer elements (not shown inFIG. 1) is positioned above the data storage media102to read data from and/or write data to the data storage media102. In the embodiment shown, the data storage media102is a rotating disc or other magnetic storage media that includes a magnetic storage layer or layers. For read and write operations, a spindle motor106(illustrated schematically) rotates the media102as illustrated by arrow107and an actuator mechanism110positions the head104relative to data tracks on the rotating media102. Both the spindle motor106and actuator mechanism110are connected to and operated through drive circuitry112(schematically shown). The head104is coupled to the actuator mechanism110through a suspension assembly which includes a load beam120connected to an actuator arm122of the mechanism110for example through a swage connection.

The one or more transducer elements of the head104are coupled to head circuitry132through flex circuit134to encode and/or decode data. AlthoughFIG. 1illustrates a single load beam coupled to the actuator mechanism110, additional load beams120and heads104can be coupled to the actuator mechanism110to read data from or write data to multiple discs of a disc stack. The actuator mechanism110is rotationally coupled to a frame or deck (not shown) through a bearing124to rotate about axis126. Rotation of the actuator mechanism110moves the head104in a cross track direction as illustrated by arrow130.

FIG. 2is a detailed illustration of the head104above the media102. The one or more transducer elements on the head104are fabricated on a slider140to form a transducer portion142of the head104. The transducer portion142shown includes write elements encapsulated in an Al2O3alumina structure to form a write assembly144of the head. As shown, the head104includes an air bearing surface146along a bottom surface150of the head or slider facing the media102. The head104is coupled to the load beam120through a gimbal spring151coupled to a top surface152of the head or slider140facing away from the media102. The media102can be a bit patterned media or other magnetic storage media including one or more magnetic recording layers.

During operation, rotation of the media or disc104creates an air flow in direction107as shown inFIG. 1along the air bearing surface146of the slider140from a leading edge154to the trailing edge156of the slider140or head. Air flow along the air bearing surface146creates a pressure profile to support the head104and slider140above the media102for read and/or write operations. As shown, the transducer portion142is formed along the trailing edge156of the slider140

FIG. 3Ais a detailed cross-sectional view of an embodiment of the write assembly144for the magnetic recording head104. As shown, the assembly144includes a main pole160having a pole tip162and a return pole164connected to the main pole160through top vias166. A magnetic flux path as illustrated by arrows170is induced in the pole tip162through the main pole160by supplying current to coils172. The direction of the flux path is controlled via the direction of the current supplied to the coils172. Coils172are embedded in a non-magnetic layer or insulating portion174between the main pole160and return pole164. The induced magnetic path provides a magnetic field proximate to the media104to induce a magnetic field or polarity in one or more magnetic recording layers180of the magnetic storage media102. In the illustrated embodiment, the media includes one or more soft magnetic underlayers (SUL)182to form a closed flux path between the main pole160and the return pole164to implement a perpendicular recording pattern where the data bits are recorded in an up/down orientation on the media. The magnetic recording layer(s)180and SUL(s)182are formed on a substrate184. One or more protective or coating layers (not shown) can be deposited over the recording layer(s)180or other layers as is known in the art.

FIGS. 3B-3Care detailed illustrations of the main pole160and pole tip162. As shown inFIG. 3B, a width of the pole160narrows in the cross track direction toward the pole tip162. The pole tip includes air bearing surface186facing the media and a beveled front surface188which intersect front surface189at an angle to provide a tapered pole tip dimension along recording tracks of the media102. As shown inFIGS. 3A and 3C, the write assembly144also includes a front shield190formed of a magnetic material forward from the main pole160and magnetically coupled to the return pole164. The front shield190is spaced from the pole tip162to form a write gap192as shown inFIGS. 3A and 3C. As shown, the write gap192extends between the beveled surface188of the pole tip and a front surface194of the front shield190spaced from the pole tip162.

As illustrated inFIG. 3C, the air bearing surface (ABS)186of the pole tip162extends from a leading edge196of the pole tip to a trailing edge198of the pole tip. The leading edge196of the ABS186has a narrower width in a cross track direction than the width of the trailing edge198of the ABS186of the pole tip. The narrow width at the leading edge196forms a generally trapezoidal air bearing pole tip surface186. The trapezoidal shape reduces adjacent track interference due to skew angle of the pole tip relative to tracks on the media102. As shown, the front shield190is spaced from the trailing edge198of the ABS186to form the write gap192as shown inFIG. 3A. The write gap192is formed of a magnetically insulating material separating the pole tip162from the front shield190. Smaller write gaps192between the pole tip162and the front shield190tend to yield higher field gradients for a given field strength to provide higher data storage density. However, efforts to reduce a width of the write gap192to increase field gradient can degrade performance due to loss of write field.

FIGS. 4A-4Cdisclose a write gap structure providing multiple write gap segments along the beveled surface188of the pole tip162. In illustrated embodiments, the multiple write gap segments provide a smaller write gap or write gap width proximate to the air bearing surface186to enhance field gradient and provide a larger write gap or write gap width behind the air bearing surface186to limit flux leakage. In the embodiment shown inFIG. 4A, the multiple gap segments are formed between a bottom bevel edge200and top bevel edge202of the beveled pole tip surface188. The multiple write gap segments include a proximal write gap segment204formed between the beveled pole tip surface188and a lower front surface205of the front shield190and a distal write gap segment206formed between the beveled pole tip surface188and an upper front surface209of the front shield190. In the embodiment shown, the lower front surface205and the upper front surface209are connected through step surface210. Step surface210extends from front edge211to a lower edge213of the upper front surface209. A plane215is perpendicular to the hearing surface146.

The lower front surface205intersects to step surface210at a front edge211and the upper front surface209intersects the step surface210forward from the front edge211in a direction away from the beveled pole tip surface188to provide the larger gap width between the beveled pole tip surface188and the upper front surface209. As shown, the lower front surface205is sloped to provide a fixed or conformal gap width between the beveled pole tip surface188and the lower front surface205. In the illustrated embodiment, the upper front surface209is also conformal with the angle of the beveled surface188but is spaced forward from the lower front surface205to provide the larger write gap width of the distal write gap segment206as described.

The narrow conformal gap width along the proximal write gap segment204provides a narrow write gap at the ABS to enhance write field gradient for high density recording, while the larger write gap width along the distal write gap segment206increases the spacing between the beveled pole tip188and shield190to reduce flux leakage to limit reductions in write field strength. As shown, step210is located between the bottom edge200and top edge202of the beveled pole tip surface188to define a transition between the proximal and distal write gap segments204,206. In the illustrated embodiment, step210is located closer to the top bevel edge202so that the wider distal gap segment206is sufficiently spaced from the air bearing surface to maintain high write field gradient, while limiting flux leakage to the shield proximate to the top edge202of the beveled pole tip surface188. In the illustrated embodiment shown, a vertical front surface212connects the upper front surface209to a top surface214of the shield190spaced from a bottom or air bearing surface of the shield190. It should be understood that application of the multiple write gap segments is not limited to the front surface including the vertical surface portion212, or particular structure shown.

In another embodiment illustrated inFIG. 4B, the write gap192includes proximal write gap segment204proximate to the air bearing surface and a distal gap segment206spaced from the air bearing surface as previously described. As shown, the front surface of the shield190includes the lower front surface205and upper front surface209between the bottom and top edges200,202of the front beveled pole tip surface188. Similar to the embodiment illustrated inFIG. 4A, the proximal write gap segment204is formed between the beveled pole tip surface and the lower front surface205of the front shield190and the distal write gap segment206is formed between the beveled pole tip surface188and upper front surface209of the front shield190.

As shown, front surface step210connects the lower front surface205to the front back surface209to provide a narrow gap along the proximal write gap segment204smaller than the write gap width along the distal write gap segment206as previously described. As shown, the lower front surface205is sloped to provide a fixed or conformal gap width between the beveled pole tip surface188and the lower front surface205of the front shield190. The upper front surface209is spaced from the lower front surface205via step210and is sloped away from the beveled surface188at a non-conformal angle to provide the larger gap width along the distal write gap segment206. In the illustrated embodiment shown, vertical front surface212connects the upper front surface209and top surface214of the shield190. Thus, as described, upper and lower front surfaces205,209are inclined at different angles to form the narrow conformal write gap at the air bearing surface and the enlarged write gap behind the air bearing surface.

FIG. 4Cillustrates another embodiment of a write assembly144including multiple proximal and distal gap segments204,206as previously illustrated inFIGS. 4A-4B. In the embodiment illustrated inFIG. 4C, the upper and lower front surfaces205,209of the front shield190are directly connected at back edge211. The upper and lower front surfaces205,209are inclined at different slope angles to form the proximal write gap width and distal write gap width having a larger dimension than the proximal write gap width. The front edge211connecting the upper and lower front surfaces205,209is located above the bottom bevel edge200and below the top beveled edge202of the pole tip162. As shown, the lower front surface205extends at a conformal angle relative to the beveled front pole tip surface188to provide a conformal write gap proximate to the air bearing surface186between the beveled pole tip surface188and the lower front surface205of the front shield190. The upper front surface209extends at a non-conformal angle to provide the distal write gap width that increases in a direction away from the air bearing surface above the front edge211to provide the larger write gap behind the air bearing surface proximate to the top edge of the beveled pole tip surface188.

FIG. 5Aillustrates process steps for fabricating embodiments of the write gap as disclosed inFIG. 4A. As shown in step300, an insulating structure is formed on the front surface and beveled surface188of the write pole162. The insulating structure is formed by depositing a first non-magnetic layer302. In the embodiment shown, the non-magnetic layer302is etched along the beveled surface188to form a conformal width along the beveled pole tip surface188. In step304, a second non-magnetic layer306is deposited on the first non-magnetic layer302. The first and second non-magnetic layers302,306can be the same material or different materials. Illustrative first and second non-magnetic materials for layers302,306include Al2O3alumina, Ru, NiCr, NiRu, Cr, SiO2or amorphous carbon A-C. The first and second non-magnetic layers302,306can be deposited using sputtering, chemical vapor deposition (CVD), molecular beam epitaxy (MBE), atomic layer deposition (ALD) e-beam evaporation, ion-beam sputtering and other deposition methods as known in the art. In one illustrated embodiment, the first non-magnetic layer302is Al2O3and the second non-magnetic layer306is amorphous carbon a-C.

In step310, a mask312is applied to a top portion of the second non-magnetic layer306proximate to the top beveled edge202. The second non-magnetic layer306is etched or milled in the non-masked areas to remove the second non-magnetic layer306from the first non-magnetic layer302in the non-masked areas as shown in step314. As shown in step316, a seed layer320is applied to the second non-magnetic layer306and the first non-magnetic layer302of the etched or milled portion to plate the front shield190. As shown in step322, the front shield is plated on the seed layer320to form the lower and upper front surfaces205,209and top surface214of the front shield190. As shown, the top surface214of the shield aligns with a top of the second non-magnetic layer306. Thus, as shown, the first non-magnetic layer forms the gap width of the proximal gap segment204and the first and second non-magnetic layers302,306form the gap width of the distal write gap segment206.

FIG. 5Billustrates process steps for fabricating another embodiment of the write gap structure illustrated inFIG. 4Bwhere like numbers are used to identify like steps in the previous embodiment. As shown inFIG. 5B, in step300the first non-magnetic layer302is formed on the front and beveled surfaces of the write pole and in step304, a second non-magnetic layer306is deposited on the first non-magnetic layer302. In step310, the mask312is applied to a portion of the second non-magnetic layer306and the second non-magnetic layer306is etched or milled in the non-masked areas to remove the second non-magnetic layer306from the first non-magnetic layer302as show in step314. Thereafter a portion of the second non-magnetic layer306is etched or milled to form an inclined angle that is different from the incline angle of the beveled surface to provide the increasing gap width along the distal write gap segment206behind the air bearing surface186. As shown in steps314,316, the front shield190is fabricated or plated on a seed layer320to form the lower and upper front surfaces205,209and conformal and non-conformal proximal and distal write gap segments204,206as previously described and shown inFIG. 4B.

FIG. 5Cillustrates process steps for fabricating another embodiment of the write gap structure as illustrated inFIG. 4Cwhere like numbers are used to identify like steps in previousFIGS. 5A-5B. The insulating structure is formed by depositing a first non-magnetic layer302and second non-magnetic layer306as shown in steps300,304. In steps310,314a bottom portion of the second non-magnetic layer306is removed to form the proximal gap segment204as previously described. In step332, the second non-magnetic layer306is etched or milled to form the sloped surface having a different inclined slope angle or non-conformal slope angle with respect to the beveled surface188to provide the larger write gap of the distal write gap segment206. Thereafter in steps316,322, the front shield190is plated on seed layer320and the first and second non-magnetic layers302,306to form the upper and lower front surfaces205,209of the front shield as previously described.

AlthoughFIGS. 5A-5Cillustrate process steps for fabricating the multiple segment write gaps described in the present application, application is not limited to the particular process steps or order described. It is to be understood that even though numerous characteristics and advantages of various embodiments of the invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the particular elements may vary depending on the particular application, while maintaining substantially the same functionality without departing from the scope and spirit of the present invention. In addition, although embodiments described herein are directed to a write gap structure for a specific write assembly including a single return pole, application is not limited to the specific embodiments or write assembly shown.