Structures for pole-tip actuation

A slider includes a slider body having a trailing edge and a leading edge. The slider also includes a thin film structure deposited in layers on the trailing edge. The thin film structure includes a write transducer configured to read and write to a storage medium. The thin film structure also includes a non-thermally activated actuator at least partially formed with the write transducer and configured to move the write transducer relative to the trailing edge.

FIELD OF THE INVENTION

The present invention relates generally to data storage systems. In particular, the present invention relates to transducers to read data from, and write data to, a magnetic recording medium.

BACKGROUND OF THE INVENTION

A typical disc drive includes a rigid housing that encloses a variety of disc drive components. The components include one or more rotating discs having data surfaces that are coated with a medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor that causes the discs to spin and the data surfaces of the discs to pass under respective aerodynamic bearing disc head sliders. Sliders carry transducers which write information to and read information from the data surfaces of the discs. The slider and transducers are often together referred to as the “head.”

Typically, transducers include an inductive recording or write transducer for generating a magnetic field that aligns the magnetic moments of the data surfaces to represent desired bits of data. The write transducer includes a magnetic core to record magnetic transitions in the magnetized medium surface of a disc. The core is magnetically coupled to a conductive coil. Electrical current flows through the conductive coil during write operation and generates magnetic flux in the core to record transitions in the magnetic surface coating of the rotating disc or other medium. The magnetic core includes a pair of poles, wherein each pole has a corresponding pole tip adjacent a surface opposing the storage medium. In a write head, for example, the pole tips are positioned on an air-bearing surface (ABS) of the slider.

Typically, the transducers also include a read element that is adapted to read magnetic flux transitions recorded to data tracks on the medium which represent the bits of data. The magnetic flux from the recording medium causes a change in the electrical resistivity of the read element, which can be detected by passing a sense current through the read element and measuring a voltage across the read element. The voltage measurement can then be decoded to determine the recorded data.

With the continuing need to meet the never ending demands for higher disc drive storage capacity, the read/write head-media spacing has been decreasing to pursue higher areal densities. Thermal pole tip protrusion can be a significant percentage of the total nominal spacing between the write transducer and disc. Thus, pole tip protrusion can effect the write performance of the disc drive. For example, the plurality of circular, concentric data tracks on the magnetic medium is divided into data sectors. As electrical current initially conducts through the conductive coil during write operation, the core is heated. The heating of the core results in thermal expansion of the pole tips. As a result of thermal expansion, the pole tips begin to protrude and push the write transducer closer to the surface of the disc, which, when thermally stabilized, results in a more efficient write process. However, there is less pole tip protrusion while the first few data sectors are written than in later data sectors when the temperature of the write transducer has stabilized. The problem may be exacerbated in a low temperature ambient environment because colder ambient temperatures cause the pole tips to recess away from the disc such that the head to media spacing is even greater in the first few data sectors.

Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.

SUMMARY OF THE INVENTION

The present invention is directed towards a slider which includes a slider body having a trailing edge and a leading edge. The slider also includes a thin film structure deposited in layers on the trailing edge. The thin film structure includes a write transducer configured to write to a storage medium. The thin film structure also includes a non-thermally activated actuator at least partially formed with the write transducer and configured to move the write transducer relative to the trailing edge.

The present invention is also directed towards a method of manufacturing a slider. The method includes, providing a slider body having a trailing edge and a leading edge. The method also includes forming a thin film structure deposited in layers on the trailing edge. Forming the thin film structure includes forming a write transducer configured to write data to a storage medium and forming a non-thermally activated actuator at least partially with the write transducer and configured to move the write transducer relative to the trailing edge.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1is a perspective view of disc drive100that includes a housing with base deck102and top cover (not shown) in which embodiments of the present invention are useful. Disc drives are common data storage systems. Disc drive100further includes a disc pack106, which is mounted on a spindle motor (not shown) by a disc clamp108. Disc pack106can include one or more discs and is illustrated with a plurality of individual discs107, which are mounted for co-rotation about axis109in the direction indicated by arrow132. Each disc surface has an associated slider110that carries read/write transducers111for communication with a disc surface. In the example inFIG. 1, slider110is supported by suspension112that is in turn attached to track accessing arm114of an actuator mechanism116. Actuator mechanism116is of the type known as a rotating moving coil actuator and includes a voice coil motor (VCM), shown generally at118. VCM118rotates actuator116about pivot shaft120to position slider110over a desired data track along an arcuate path122between a disc inner diameter124and a disc outer diameter126. Slider110is coupled to suspension112through a gimbal attachment which allows slider110to pitch and roll as it rides on an air-bearing surface (ABS) of disc107. Slider110supports transducers111at a trailing edge. Transducers111include separate reading and writing elements for reading data from, and recording data to disc107.

During operation, as disc107rotates, air is dragged under the ABS of slider110in a direction approximately parallel to the tangential velocity of disc107. As the air passes beneath the bearing surfaces, air compression along the air flow path causes the air pressure between the disc surface and the bearing surfaces to increase, which creates a hydrodynamic lifting force that counteracts a load force provided by suspension112. This hydrodynamic lifting force causes the slider110to “fly” above, and in close proximity, to the disc surface of disc107.

VCM118is driven by electronic circuitry130based on signals generated by transducers111and a host computer (not shown). During operation, electronic circuitry130receives position information indicating a portion of disc107to be accessed. Electronic circuitry130receives the position information from an operator, from a host computer, or from another suitable controller. Based on the position information, electronic circuitry130provides a position signal to actuator mechanism116. Once transducers111are appropriately positioned over a specified track on disc107, electronic circuitry130then executes a desired read or write operation.

FIG. 2is a section view of a portion of read/write transducers111and disc107. Transducers111include write transducer234and read transducer236which are both formed in the thin film structure deposited on the trailing edge of the slider. Read transducer236includes a read element238that is spaced between a first pole240, which operates as a top shield, and a bottom shield242. The top and bottom shields operate to isolate read transducer236from external magnetic fields that could affect sensing bits of data recorded on disc107. Write transducer234includes second pole244and first pole240. The first and second poles240and244are connected at back via248. A conductive coil250extends between first pole240and second pole244and around back via248. An insulating material252electrically insulates conductive coil250from first and second poles240and244. First and second poles240and244include first and second pole tips256and254, respectively, which face the surface of disc107and form a portion of the ABS259.

Thermal pole tip protrusion can be a significant percentage of the total nominal spacing between transducers111and the surface of disc107, which has a high areal density. As electrical current conducts through conductive coil250during write operation, write transducer234is heated. The heating of write transducer234results in thermal expansion of the pole tips254and256. As a result of thermal expansion, pole tips254and256protrude and push write transducer234closer to disc107, which, when thermally stabilized, result in a more efficient write process. However, there is less pole tip protrusion while the first few data sectors of disc107are written than in later data sectors when the temperature of write transducer234has stabilized. Thus, thermal pole tip protrusion can detrimentally effect the write performance of the disc drive. While a variety of different types of transducers can be used, the term pole tip protrusion is used herein to refer to protrusion of the write transducer from the head into the head-media spacing. To prevent data errors written to disc107before write transducer234is thermally stabilized, the present invention is a non-thermally activated actuator formed with transducers111and the thin film structure. This non-thermally activated actuator allows fast response time with precise control of transducers111, without the need or issues associated with adding thermal energy to transducers111. As defined herein, a “non-thermally activated actuator” is an actuator having an actuation mechanism which is not thermally induced. For example, magnetostrictive, piezoelectric and shape memory alloys are such actuators. Actuators that rely on thermal expansion, even if “actuated” by a voltage or current, are considered to be thermally activated actuators.

FIG. 3-1illustrates a schematic view of slider310-1in accordance with an embodiment of the present invention. Slider310-1includes slider body370, base coat358and thin film structure376. Slider body370includes trailing edge372and bearing surface359. For example, bearing surface359is an air bearing surface (ABS). Base coat358is deposited on trailing edge372to electrically insulate slider body370from thin film structure376. Thin film structure376is deposited on base coat358in layers and includes write transducer334, read transducer336and non-thermally activated actuator368-1. As schematically illustrated inFIG. 3-1, write transducer334is formed and deposited with non-thermally activated actuator368-1on base coat358. Thereafter, read transducer336is deposited on write transducer334. Actuator368-1is positioned coplanar with write transducer334and configured to strain write transducer334in a direction369that is perpendicular to bearing surface359. The resulting strain causes the write poles of write transducer334to protrude perpendicularly to bearing surface359as depicted by dashed line374. Actuator368-1can also be configured to strain write transducer334in directions371that are parallel to bearing surface359. The resulting strain causes fine-tune placement of write transducer334over tracks on the disc, such as disc107, during track-following mode.

FIG. 3-2is an enlarged schematic view of write transducer334and actuator368-1ofFIG. 3-1in accordance with an embodiment of the present invention. Write transducer334includes first pole340and second pole344. The first and second poles340and344are connected at back via348. A conductive coil350extends between first pole340and second pole344and around back via348. An insulating material352electrically insulates conductive coil350from first and second poles340and344. First and second poles340and344include first and second pole tips356and354, respectively, which face the surface of a disc and form a portion of ABS359.

Actuator368-1includes stress field373and actuating material375. Stress field373is tailored to the geometry of actuating material375by appropriately depositing films with large and small stiffnesses into layers. As shown inFIG. 3-2, stress field373is deposited between write transducer334and actuating film375. Stress field373includes low stiffness layer370interposed between two high stiffness layers372. The stiffness of layers370and372are classified by a modulus of elasticity, or Young's modulus, which is defined as the linear relationship between the stress and the strain of a particular material. For example, films having a large Young's modulus are silicon nitrides and films having a small Young's modulus are silicon oxynitrides. Stress field373produces a large stress magnitude near the top and bottom of writer poles340and344and a small stress magnitude near coils350.

FIG. 3-3is a schematic view of slider310-3in accordance with an embodiment of the present invention. Slider310-3includes slider body370, base coat358and thin film structure376. Slider body370includes trailing edge372and bearing surface359. Base coat358is deposited on trailing edge372to electrically insulate slider body370from thin film structure376. Thin film structure376is deposited in layers on base coat358and includes write transducer334, read transducer336and non-thermally activated actuator368-3. As schematically illustrated inFIG. 3-3, write transducer334and read transducer are formed and deposited with non-thermally activated actuator368-3on base coat358. Actuator368-3is positioned coplanar with both write transducer334and read transducer336. Actuator368-3is configured to strain write transducer334and read transducer336in a direction369that is perpendicular to bearing surface359. The resulting strain causes the write poles of write transducer334to protrude perpendicularly to bearing surface359as well as the read element of read transducer336. This protrusion is depicted by dashed line374. Actuator368-3can also be configured to strain write transducer334and read transducer336in directions371that are parallel to bearing surface359. The resulting strain causes fine-tune placement of write transducer334and read transducer336over tracks on the disc during track-following mode.

Also shown inFIG. 3-3are optional first compliant layer361-3and optional second compliant layer365-3and their corresponding first and second portions360,362,364and366as discussed inFIG. 3-1. In some embodiments ofFIG. 3-3, only first portion360of first compliant layer361-3and first portion364of second compliant layer365-3are deposited within thin film structure376. First portion360of first layer361-3is deposited between base coat358and write transducer334. First portion364of second compliant layer365-3is deposited on read transducer336such that little to no deformation takes place outside of the write poles and read element. In other embodiments of the present invention, both first compliant layer361-3and second compliant layer365-3are deposited within thin film structure376. First compliant layer361is deposited between base coat358and both write transducer334and actuator368-3. Second compliant layer365-3is deposited on both read transducer336and actuator368-3such that little to no deformation takes place outside of the write poles, the read element and actuator368-3. In yet other embodiments ofFIG. 3-3, only first compliant layer361-3is deposited between base coat358and both write transducer334and actuator368-3such that little to no deformation takes place outside of thin film structure376. Those skilled in the art will recognize that multiple configurations of optional first compliant layer361-3, optional second compliant layer365-3and their corresponding portions360,362,364and366can be used. In addition, other layers containing compliant films may be deposited in thin film structure376as long as the layers increase the deformation induced at bearing surface359, isolate the deformation caused by stress field373(shown inFIG. 3-2) or reduce the stress in the read transducer336.

FIG. 4-1illustrates a schematic view of slider410-1in accordance with an embodiment of the present invention. Slider410-1includes slider body470, base coat458and thin film structure476. Slider body470includes trailing edge472and bearing surface459. Base coat458is deposited on trailing edge472to electrically insulate slider body470from thin film structure476. Thin film structure476is deposited on base coat458in layers and includes write transducer434, read transducer436and non-thermally activated actuator468-1. As schematically illustrated inFIG. 4-1, read transducer436is formed and deposited on base coat458. Thereafter, write transducer434is formed and deposited with actuator468-1on read transducer436. Actuator468-1is positioned coplanar with write transducer434and configured to strain write transducer434in a direction469that is perpendicular to bearing surface459. The resulting strain causes the write poles of write transducer434to protrude perpendicularly to bearing surface459as depicted by dashed line474. Actuator468-1can also be configured to strain write transducer434in directions471that are parallel to bearing surface459. The resulting strain causes fine-tune placement of write transducer434and read transducer436over tracks on the disc during track-following mode.

Also shown inFIG. 4-1are an optional first compliant layer461-1and an optional second compliant layer465-1and their corresponding first and second portions460,462,464and466as were discussed in previous embodiments. In some embodiments of the present invention, only first portion460of first compliant layer461-1and first portion464of second compliant layer465-1are deposited within thin film structure476. First portions460and464are deposited on either side of write transducer434such that little to no deformation takes place outside of the write poles. In other embodiments of the present invention, both first compliant layer461-1and second compliant layer465-1are deposited within thin film structure476. First compliant layer461-1and second compliant layer465-1are deposited on either side of write transducer434and either side of actuator468-1such that little to no deformation takes place outside of the write poles and actuator468-1. In yet other embodiments of the present invention, only first compliant layer461-1is deposited between read transducer436and both write transducer434and actuator468-1such that little to no deformation takes place outside of thin film structure476. Those skilled in the art will recognize that multiple configurations of optional first compliant layer461-1, second compliant layer465-1and their corresponding portions460,462,464and468can be used. In addition, other layers containing compliant films may be deposited in thin film structure476as long as the layers increase the deformation induced at bearing surface459, isolate the deformation caused by a stress field (not shown inFIG. 4-1) or reduce the stress in the read transducer436.

FIG. 4-2is a schematic view of slider410-2in accordance with an embodiment of the present invention. Slider410-2includes slider body470, base coat458and thin film structure476. Slider body470includes trailing edge472and bearing surface459. Base coat458is deposited on trailing edge472to electrically insulate slider body470from thin film structure476. Thin film structure476is deposited on base coat458and includes write transducer434, read transducer436and non-thermally activated actuator468-2. As schematically illustrated inFIG. 4-2, read transducer436is formed and deposited on base coat458. Thereafter, transducer434is formed and deposited on read transducer436. Both read transducer436and write transducer434are formed and deposited with non-thermally activated actuator468-2. Actuator468-2is positioned coplanar with both write transducer434and read transducer436. Actuator468-2is configured to strain write transducer434and read transducer436in a direction469that is perpendicular to bearing surface459. The resulting strain causes the write poles of write transducer434to protrude perpendicularly to bearing surface459as well as the read element of read transducer436. This protrusion is depicted by dashed line474. Actuator468-2can also be configured to strain write transducer434and read transducer436in directions471that are parallel to bearing surface459. The resulting strain causes fine-tune placement of write transducer434and read transducer436over tracks on the disc during track-following mode.

Also shown inFIG. 4-2are optional first compliant layer461-2and optional second compliant layer465-2and their corresponding first and second portions460,462,464and466as discussed in previous embodiments. In some embodiments of isFIG. 4-2, only first portion460of first compliant layer461-2and first portion464of second compliant layer465-2are deposited within thin film structure476. First portion460of first compliant layer461-2is deposited between base coat458and read transducer436. First portion464of second compliant layer465-2is deposited on write transducer434such that little to no deformation takes place outside of the write poles and the read element. In other embodiments of the present invention, both first compliant layer461-2and second compliant layer465-2are deposited within thin film structure476. First layer461is deposited between base coat458and both read transducer436and actuator468-2. Second compliant layer465-2is deposited on both write transducer436and actuator468-2such that little to no deformation takes place outside of the write poles, read element and actuator468-2.

In yet other embodiments ofFIG. 4-2, only first compliant layer461-2is deposited between base coat458and both read transducer436and actuator468-2such that little to no deformation takes place outside of thin film structure476. Those skilled in the art will recognize that multiple configurations of optional first compliant layer461-2, optional second compliant layer465-2and their corresponding portions460,462,464and466can be used. In addition, other layers containing compliant films may be deposited in thin film structure476as long as the layers increase the deformation induced at bearing surface459, isolate the deformation caused by a stress field (not shown inFIG. 4-2) or reduce the stress in the reader.

As illustrated inFIGS. 3-1and3-2, write transducer344and actuator368are deposited prior to read transducer336and are coplanar with each other. As illustrated inFIG. 4-1, read transducer436is deposited prior to both write transducer434and actuator468. In some embodiments of the present invention, the actuating material is deposited at room temperature. In this case, the read transducer can be deposited prior to the write transducer as illustrated inFIGS. 4-1and4-2. In other embodiments of the present invention, actuator368,468is deposited by physical vapor deposition, chemical vapor or sol-gel deposition (a process involving the transition of a system from a liquid into a gel phase). These methods of deposition may require high-temperature annealing. Thus, the write transducer is preferably deposited prior to the read transducer to prevent excessive heating of the read transducer as illustrated inFIG. 3-1. In those embodiments where heat treatment of the actuating material is needed, a chemically and mechanically polished (CMP) step can follow. The more the actuating material is heat treated the larger the strain.

FIGS. 5-1through5-3illustrate embodiments showing specific types of actuators deposited in the thin film structure. Although these specific actuators are illustrated as being deposited with the write transducer, those skilled in the art will appreciate that these specific actuators can be also deposited with the read transducer and write transducer as shown in previous embodiments. In addition,FIGS. 5-1through5-3illustrate the read transducer deposited on the write transducer. Those skilled in the art will appreciate that the write transducer can be deposited on the read transducer as shown in previous embodiments.

FIG. 5-1is a schematic view of slider510-1in accordance with an embodiment of the present invention. Slider510-1includes slider body570, base coat558and thin film structure576. Slider body570includes trailing edge572and bearing surface559. Base coat558is deposited on trailing edge572to electrically insulate slider body570from thin film structure576. Thin film structure576is deposited on base coat558and includes write transducer534, read transducer536and non-thermally activated actuator568-1. As schematically illustrated inFIG. 5-1, actuator568-1includes actuating material575, coils580and yoke584. Coils580of actuator568-1are deposited and formed with coils550of write transducer534. In some embodiments ofFIG. 5-1, actuating material575can be a magnetostrictive material. For example, the magnetostrictive material can be rare-earth transition metal alloys, such as TbFe and TbFeDy. In other embodiments ofFIG. 5-1, actuating material575can be a ferromagnetic shape memory alloy having energy associated with rotating the magnetization of the martensitic phase that is higher than energy associated with the twin-boundary motion. Examples of shape memory alloys with this characteristic include NiMnGa and FePd.

Regardless of whether magnetostrictive materials or shape memory alloys are used as the actuating material inFIG. 5-1, actuator568-1is driven by electrically conducting coils580surrounded by yoke584. The current running through coils580induces a magnetic field in actuator material575that is perpendicular to bearing surface559. The magnetic field causes actuator material575to strain in a direction perpendicular to bearing surface559. The strain is transmitted and enhanced through stress field573as discussed in previous embodiments. The resulting strain causes write poles540and544of write transducer534to protrude perpendicularly to bearing surface559at their pole tips. This protrusion is depicted by dashed line574.

Slider510-1also includes optional first compliant layer561, optional second compliant layer565and their corresponding portions560,562,564and566as discussed in previous embodiments. In the case of shape memory alloys, actuator568-1should be deposited on portion562and portion566should be deposited on actuator568-1to allow free twin-boundary motion.

FIG. 5-2is a schematic view of slider510-2in accordance with an embodiment of the present invention. Slider510-2includes slider body570, base coat558and thin film structure576. Slider body570includes trailing edge572and bearing surface559. Base coat558is deposited on trailing edge572to electrically insulate slider body570from thin film structure576. Thin film structure576is deposited on base coat558and includes write transducer534, read transducer536and non-thermally activated actuator568-2. As schematically illustrated inFIG. 5-2, actuator568-2includes actuating material575and contacts581and582. In some embodiments ofFIG. 5-2, actuating material575can be a piezoelectric material. Examples of piezoelectric materials include lead zirconate titanate (PZT), barium zirconate titanate, or other suitable piezoelectric materials, such as ceramics single crystals or polymers, which exhibit the desired piezoelectric properties. In other embodiments ofFIG. 5-2, actuating material575can be a magnetoelectric composite. For example, the magnetoelectric composites can be composites of rare-earth transition metal alloys, such as TbFeDy and piezoelectric materials.

Regardless of whether magnetoelectric composites or piezoelectric materials are used as the actuating film inFIG. 5-2, a voltage is applied across contacts581and582such that actuator material575will expand in a direction perpendicular to bearing surface559. The voltage differential causes actuator material575to strain and is transmitted through stress field573. This strain causes write poles540and544of write transducer534to protrude perpendicularly to bearing surface559at their pole tips. This protrusion is depicted by dashed line574. Those skilled in the art will recognize that actuating material575can be deposited on contacts581and582(shown inFIG. 5-2) or contacts581and582can be deposited on actuating material575. Slider510-2also includes optional first compliant layer561, optional second compliant layer565and their corresponding portions560,562,564and566as discussed in previous embodiments.

FIG. 5-3is a schematic view of slider510-3in accordance with an embodiment of the present invention. Slider510-3includes slider body570, base coat558and thin film structure576. Slider body570includes trailing edge572and bearing surface559. Base coat558is deposited on trailing edge572to electrically insulate slider body570from thin film structure576. Thin film structure576is deposited on base coat558and includes write transducer534, read transducer536and non-thermally activated actuator568-3. As schematically illustrated inFIG. 5-3, actuator568-3includes actuating material575interposed between contacts581and582. In some embodiments ofFIG. 5-2, actuating material575can be a piezoelectric material. Examples of piezoelectric materials are discussed above. In other embodiments ofFIG. 5-3, actuating material578can be a magnetoelectric composite. An example of a magnetoelectric composite is discussed above.

Regardless of whether magnetoelectric composites or piezoelectric materials are used as the actuating film inFIG. 5-3, once a voltage is applied across contacts581and582, actuator material578will shear or distort in shape. The shearing causes strain in a direction perpendicular to bearing surface559. The voltage differential causes actuator material575to strain and is transmitted through stress field573. This strain results in write poles540and544of write transducer534to protrude perpendicularly to bearing surface559at their pole tips. This protrusion is depicted by dashed line574. Slider510-3also includes optional first compliant layer561, optional second compliant layer565and their corresponding portions560,562,564and566as discussed in previous embodiments.

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 for the system while maintaining substantially the same functionality without departing from the scope and spirit of the present invention. Although the present invention was directed to a non-specific bearing surface, it should be noted that any type of air bearing surface without 100% self-compensation can be used in the present invention. In addition, although the preferred embodiment described herein is directed to a slider for carrying transducers, it will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other types of sliders, without departing from the scope and spirit of the present invention.