Method for forming an air bearing surface on a slider

Embodiments include a slider having a silicon body and at least one carbide pad structure embedded therein. At least one head structure for reading and/or writing data is located on the silicon body. The silicon body includes an air bearing surface on which the head is located. The air bearing surface also includes at least a portion of the carbide pad structure thereon. In one aspect, the metal carbide structure may be made from a material such as titanium carbide, zirconium carbide, vanadium carbide, tungsten carbide, or molybdenum carbide. In another aspect, the head may be located on the air bearing surface between carbide pad structures.

FIELD OF THE INVENTION

Embodiments of the present invention relate generally to disk drive systems and to read/write elements and slider devices within the systems.

DESCRIPTION OF RELATED ART

Magnetic storage systems typically include a rotatable magnetic disk having concentric data tracks defined for storing data, and a magnetic recording head or transducer for reading data from and writing data to the various data tracks. In typical disk drive systems, a stack of one or more magnetic disks is mounted over a spindle on a drive motor. The system also includes a head actuator for moving the magnetic recording head relative to the disk surfaces, and electronic circuitry for processing signals to implement various functions of the disk drive.

The head is attached to a carrier or slider having an air bearing surface which is supported during operation adjacent to the data surface of the disk by a cushion of air generated by the rotating disk. The terms “head” and “slider” are sometimes both used to refer to the slider having a head attached thereon. The slider design affects the efficiency, density, speed and accuracy with which the data can be read and written to the disk. Recording density generally depends on the separation distance between the recording element of the head and the disk. As a result, lower flying heights are usually desired to achieve high areal density recording. Lower flying heights, however, can lead to undesirable interactions between the head and the disk.

As the disk generally includes a hard carbon coating, the slider is typically fabricated from a hard ceramic material so that any interactions between the disk and air bearing surface of the slider will not result in premature wear or breakage of the slider. In addition, the slider material should be relatively inert so that no chemical reactions take place on the air bearing surface. As illustrated inFIG. 1, sliders are usually derived from a wafer100made from a ceramic material such as a mixture of aluminum oxide (Al2O3) and titanium carbide (TiC). The components of each read/write device are formed or deposited on a surface12of the wafer10and the wafer10is diced into rows such as row20illustrated inFIG. 2. The row20has an end surface12having the read/write device and a row face that is processed, usually by polishing and/or etching, to form an air bearing surface22. The row20is then diced into individual sliders30having an air bearing surface22and a read/write device surface12on which the read/write device is preferably located at a central position32, as illustrated inFIG. 3.

Fabricating a slider from silicon presents problems because silicon is relatively soft when compared with slider materials such as Al2O3/TiC. This can lead to durability problems. In addition, silicon displays undesirable start/stop behavior on a disk when compared with other materials.

SUMMARY

Preferred embodiments of the present invention relate to disk drive systems and components therein, including sliders and read/write elements thereon.

One embodiment includes a slider structure including a silicon body having an air bearing surface. The air bearing surface includes a silicon surface region and a metal carbide surface region. The metal carbide surface region is a part of a metal carbide structure embedded in the silicon body.

Another embodiment includes a slider having a silicon body and at least one pad structure embedded therein. At least one head structure for reading and/or writing data is located on the silicon body. The silicon body includes an air bearing surface on which the head is located. The air bearing surface also includes at least a portion of the pad structure thereon.

Still another embodiment includes a disk drive for reading and writing disks. The disk drive includes at least one disk and a read/write head associated with the surface of the disk. The disk drive includes a slider onto which the read/write head is provided. The slider includes a silicon body and an air bearing surface on the silicon body. The air bearing surface includes a silicon surface region and a metal carbide surface region, with the metal carbide surface including a portion of the at least one carbide structure embedded in the silicon body. The disk drive also includes an actuator for supporting the slider and positioning the head across the disk, as well as a rotatable hub for mounting the disk.

Embodiments also relate to methods for forming an air bearing surface on a slider. One such embodiment includes providing a silicon slider body and forming at least one trench on a portion of one side of the silicon body. A carbide or nitride structure is formed in the trench. Preferably the air bearing surface includes both a portion of the silicon body and a portion of the carbide structure. Certain embodiments may also include forming at least one of a read element and a write element on the air bearing surface after forming the carbide or nitride structure.

In one aspect of certain embodiments, a carbide structure may be formed by a process including filling the trench with a metal carbide and anhydrous metal chloride material and heating the material to produce a melt. The material is then cooled and the chloride material formed from the melt is removed. Preferably the remaining carbide material is then planarized.

Still another embodiment relates to a method for forming a slider including forming at least one trench into a silicon body and forming an air bearing surface pad structure in the trench that extends to a position at or above the silicon body. A read/write head is then formed on the silicon body after forming the air bearing surface pad structure.

DETAILED DESCRIPTION

Preferred embodiments of the present invention are described with reference toFIGS. 4–13. While the invention is described in terms of the best mode for achieving this invention's objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the invention.

Formation of silicon based sliders for read/write heads for recording applications has not been favored because single crystal silicon has a lower hardness and less resistance to chipping than other materials such as aluminum oxide/titanium carbide. The hardness and resistance to chipping are important in the regime of near contact recording, for durability purposes. Certain preferred embodiments of the present invention relate to processes and structures which may relate to a silicon slider including at least one hard carbide pad embedded in a portion of the silicon slider air bearing surface prior to forming the read/write head element on the air bearing surface of the slider.

Preferred structures provide numerous advantages including the ability to efficiently produce advanced read/write structures after forming the air bearing surface. This means that the processing steps used for forming the air bearing surface which may, for example, include elevated temperatures, will not effect the read/write structure. By forming the read/write head element on the air bearing surface, preferred embodiments also provide the ability to precisely control the height of the read/write head elements, which permits the elements to be spaced very close to the surface of a disk during operation.

Processing steps according to one embodiment of the present invention are described below with reference toFIGS. 4–8. A silicon wafer or substrate100may be masked and etched as known in the art to form one or more trenches or openings102in the surface of the substrate100, as illustrated inFIG. 4. If desired, an optional layer104of, for example, a material including titanium, may be deposited over all or a portion of the silicon substrate100. The layer100may act as an adhesive and/or barrier layer between the silicon and the layer106to be deposited in the openings102between the layer106and the silicon substrate100. (FIG. 5) A layer106including the metal carbide precursor materials is formed over the silicon substrate100and within the openings102.

In one embodiment, an anhydrous metal chloride is used to create the carbide layer106through an interaction with a metal carbide which may include, for example, calcium carbide and/or aluminum carbide. The metal carbide precursor layer106may be deposited using a technique such as, but not limited, to physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD), or a spray deposition technique. The metal carbide precursor layer106is then heated to a temperature sufficient to produce a melt (for example, at least 450° C.). The heating cycle may be very short, for example, in certain embodiments, less than one minute. The heating may take place at atmospheric or vacuum pressure. A short anneal step at higher temperature may also be optionally included to insure the reaction is complete. The wafer including the layer106is then cooled and the layer106includes a material including the reacted products of a metal carbide and a metal chloride region. After cooling, the surface may be rinsed with water and methanol to remove the calcium chloride. In certain embodiments the annealing may be carried out at about 800° C. to about 1000° C. for a time of up to about 48 hours.

After the carbide layer106is formed, an etch back and/or polishing step may be carried out to planarize the carbide as desired. In certain embodiments, the carbide is planarized to the same level with the silicon (FIG. 7) and then the non-air bearing surface pad areas etched to a predetermined depth so that the carbide layer regions106remaining are raised above the level of the silicon100, as illustrated inFIG. 8. These raised carbide layer regions106may serve as the rails of the air bearing surface of the slider during operation. The desired read/write structure is preferably formed in or on the silicon substrate100between the raised carbide layer regions106. In alternative embodiments, the carbide layer regions may be processed to be at any desired level. Processing methods by which the carbide layer height can be controlled include, for example, polishing, etching, and ion milling.

FIGS. 9–12illustrate several views of a slider200according to certain embodiments of the present invention having a plurality of carbide structures such as pads202embedded in the silicon substrate201. The pads202may in certain embodiments be formed from a process such as that described above in conjunction withFIGS. 4–8or may be formed by other processes such as, but not limited to a physical vapor deposition or chemical vapor deposition (CVD) method that does not require a melt step as described above.

FIG. 9is a top view of the air bearing surface206of the slider200showing the relative locations of a plurality of carbide pads202, a read/write device208and electrical wire connects210.FIG. 10is a side cross-sectional view of the slider200along the line A–A′.FIG. 11is a side cross-sectional view of the slider200along the line B–B′.FIG. 12is a magnified view of a portion of the slider200ofFIG. 11.

The slider includes openings or trenches214into which the carbide pad structures202are disposed. The air bearing surface206may include a plurality of carbide pads202that are substantially rectangular in shape when viewed from above the air bearing surface. The carbide pads (and the trenches) may be formed into any desired shape. In addition, the air bearing surface may alternatively include a single pad if desired. The size, shape, and number of pads may depend on a variety of factors, including the flight characteristics of the slider and the position of the read/write device thereon. The terms “read/write device,” “read/write head,” “read/write structure” and “head” as used herein may refer to a structure including, but not limited to one or more read elements, one or more write elements, or a combination of read and write elements.

FIG. 9also illustrates the relative locations of the read/write device208and the electrical wire connects210according to one preferred embodiment. The read/write device is preferably formed on the silicon air bearing surface206between carbide pads202at a position equal to or below the height of the carbide pads202. Electrical connections to the read/write device may be made by forming trenches or grooves216into which the electrical wire interconnects210are formed. The dashed line area224inFIG. 12illustrates a portion of a trench216through which the interconnect210extends to contact the read/write device208. The interconnect region210illustrated inFIGS. 9–11may be made up of a conducting: layer222and an insulating layer220separating the conducting layer from the silicon slider material. The trench216may be formed by masking and etching the substrate201and may in certain embodiments be lined with an electrically insulating material220such as, for example, SiO2, followed by a conducting layer222. The conducting layer222may be formed from a variety of materials such as, for example, aluminum, copper, or alloys including aluminum and/or copper. If the conducting layer222overfills the trench216, a method such as a masking and etching operation may be used to remove the overfilled material. This may be necessary because a damascene polishing step would be difficult to perform due to the carbide pads202, which, as illustrated inFIGS. 10–12, are preferably raised above the silicon substrate201surface. Alternatively the electrical interconnects210may be made on or above the surface of the substrate201. The electrical interconnects210may preferably extend to an end of the air bearing surface206as illustrated inFIG. 9.

Certain preferred embodiments include two sets of trenches, such as, for example, the trenches214and216. The trenches may be formed at the same time if desired. One set of trenches214may include an adhesion or barrier layer therein between the silicon and the carbide pad202. The other set of trenches216may include an insulating layer220between the silicon and the conductive layer222. Any overfill of material from the trenches may be removed simultaneously if desired, using a method such as polishing. Once the air bearing surface pads are planarized, the non-air bearing surface pad areas may be etched or milled down below the air bearing surface. Further processing may then proceed on the recessed silicon surface.

If desired, a coating layer such as a hard carbon or a polymer may be deposited over at least a portion of the air bearing surface. Such a layer may in certain embodiments be deposited near the edges205of the air bearing surface to protect the slider from damage.

Embodiments of the present invention provide numerous advantages over other slider structures. Typically, the read/write structure is formed first and then the air bearing surface is formed. The air bearing surface formation may include steps such as depositing a layer over the air bearing surface and etching and/or polishing the air bearing surface. These steps may use elevated temperatures and/or chemicals which can harm the read/write head structure. By forming the air bearing surface first and then forming the read/write structure, as in certain preferred embodiments of the present invention, the air bearing surface processing steps will not affect the read/write structure.

In addition, forming the slider from silicon permits a variety of read/write device structures and circuitry to be formed directly on or in the slider material, thus simplifying the process. Advanced read/write structures such as those having an AFM (atomic force microscopy) tip, or other fine, fragile structures can be formed on the air bearing surface without risk of a later processing step that requires processing conditions that might degrade the read/write device structure. A wide variety of read/write structures may be used in embodiments of the present invention. Other types read/write structures which may be utilized include, but are not limited to magnetic tunnel junction structures, thin film structures, magneto-restrictive (MR) structures, and giant magneto-resistive (GMR) structures.

Furthermore, the carbide pads and read/write structure can be formed to minimize the distance of the read/write structure from the disk during operation. In certain preferred embodiments the read/write structure is formed on the air bearing surface, which permits it to be located at a height so that it can be brought very close to the disk surface during operation. This is important because to achieve high resolution, the read/write structure should generally be very close to the disk. Mass producing a read/write structure, in which the structure is very close to the disk, is difficult using conventional read/write head and slider edge type configurations due to difficulties in dicing and handling the individual sliders precisely. By forming the read/write structure on the air bearing surface according to certain preferred embodiments of the present invention, a lower level of dicing precision is necessary, thus enabling a higher production yield.

As illustrated inFIGS. 9–11, the read/write structure may be formed between the carbide pads on the air bearing surface. Alternatively the read/write structure may be located at another location on the slider such as, for example, the trailing edge.

In another aspect of embodiments of the present invention, a variety of materials may be used as pad structures within the air bearing surface of a slider. Some preferred materials include metal carbides such as titanium carbide, zirconium carbide, vanadium carbide, tungsten carbide and molybdenum carbide. More specifically, these carbides may include TiC, ZrC, V8C7, WC, and Mo2C. Other carbides may also be used, preferably other than silicon carbide (SiC) and those having a hardness greater than that of SiC. Certain embodiments may also utilize other materials such as nitrides, for example, aluminum nitride (AIN) as a pad material.

FIG. 13illustrates portions of a disk drive system300according to another embodiment of the present invention. The system includes one or more disks302stacked above one another. The disks302are capable of storing data in concentric tracks. Both sides of the disks302may be available for storage, and the stack may include any number of such disks302. The disks302are mounted to a spindle304. The spindle304is attached to a spindle motor, which rotates the spindle304and the disks302to provide read/write access to the various portions of the concentric tracks on the disks302.

The disk drive system300may also include an actuator assembly306including voice coil motor assembly308, which controls a head arm assembly which may include a positioner arm310and a suspension assembly312. The suspension assembly312includes a slider200at its distal end. The slider200may be similar to the slider200described above and illustrated inFIGS. 9–12. Other slider structures could also be used if desired. Although only one slider200is shown, it will be recognized that the disk drive assembly300may include one or more sliders for each side of each disk302included in the drive. The positioner arm310may also include a pivot314around which the positioner arm310moves. A flexible printed circuit member316may carry digital signals between a chip318and the actuator assembly306. One or more electrical conductors320are routed along the positioner arm310and suspension312to carry electrical signals to and from the read/write device and slider200. The electrical conductors may be fabricated from a conductive material such as, for example, copper, aluminum, or alloys of these or other materials.

It will, of course, be understood that modifications of the present invention, in its various aspects, will be apparent to those skilled in the art. Other embodiments are possible, their specific features depending upon the particular application. For example, the preferred slider body material is single crystal silicon, although polycrystalline silicon or other materials could also be used. Furthermore, a variety of disk drive configurations, geometries, and components may be may be employed in disk drive systems in addition to those discussed above.