Dynamic magnetic information storage or retrieval – Fluid bearing head support – Disk record
Reexamination Certificate
2001-04-10
2003-04-29
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Fluid bearing head support
Disk record
C360S235300, C360S234300
Reexamination Certificate
active
06556380
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to recording head sliders of disk drive assemblies. More particularly, it relates to trapezoidal-shaped silicon sliders.
BACKGROUND ART
Hard disk drives utilizing magnetic data storage disks are used extensively in the computer industry. A head/disk assembly typically includes one or more commonly driven magnetic data storage disks rotatable about a common spindle. At least one head actuator moves a plurality of magnetic read/write heads radially relative to the disks to provide for reading and/or writing of data on selected circular concentric tracks of the disks. Each magnetic head is suspended in close proximity to one of the recording disks and supported by an air bearing slider mounted to the flexible suspension. The suspension, in turn, is attached to a positioning actuator.
During normal operation, relative motion between the head and the recording medium is provided by the disk rotation as the actuator dynamically positions the head over a desired track.
The relative motion provides an air flow along the surface of the slider facing the medium, creating a lifting force. The lifting force is counterbalanced by a known suspension load so that the slider is supported on a cushion of air. Air flow enters the leading edge of the slider and exits from the trailing end. The head resides toward the trailing end, which tends to fly closer to the recording surface than the leading edge.
Conventional magnetic recording head sliders are typically made from wafers of a two-phase ceramic, TiC/Al
2
O
3
, also called Al-TiC. After the thin film processing to prepare the recording heads is performed on the Al-TiC wafers, the sliders are then formed. The sliders are fabricated by cutting, grinding and lapping the wafer made of the above material. This involves a series of shaping and polishing operations, and also the formation of an air bearing, usually using dry etching, on the polished surface.
Normally, magnetic recording head sliders are formed to have a rectangular prism shape, having a rectangular footprint. Occasionally an unwanted process deviation, such as substrate misalignment or uneven lapping pressure, leads to substrate non-rectangularity. Alternatively, sliders have been fabricated having a triangular shape.
The nature of magnetic recording has changed in the last several years from one in which a slider comes to rest on the recording medium, either in a data field or a special landing zone, to one in which a slider is never allowed to come to rest anywhere upon the recording medium. This is accomplished through the use of a “load/unload” device, which is essentially a ramp containing a resting place for the suspension/slider assembly. A metal extension from the suspension is used to hold the assembly in place. One problem with this approach is that as the slider and suspension are swung back onto the disk from the rest position, there is the potential for disk damage as the leading edge of the slider and longitudinal edges contact the disk. To prevent such disk damage, the slider is mounted on the suspension with a positive pitch (the leading edge is higher than the trailing edge with respect to the disk), which requires that the suspension be bent in a particular way.
FIG. 1
is a schematic diagram showing a magnetic recording system
100
including a recording medium
102
and a rectangularly shaped slider
104
mounted on a flexure
108
connected to a suspension
106
through a gimbal
110
. The flexure
108
is bent to provide a positive pitch &thgr;.
U.S. Pat. No. 4,809,103, issued to Lazzari on Feb. 28, 1989, discloses a head slider for magnetic recording on a recording media. The slider is a silicon wafer with a first face parallel to the recording media and a second opposite face parallel to the first face. A flat magnetic head is integrated into the silicon wafer in the first face, and an electronic circuit is integrated in either first or second face. The slider is thinner than a conventional slider. However, there is the potential for damage of the recording media as the edges of the slider make contact with the disk.
An article entitled “A New Sub-Femto Slider for Mass Production Planar Silicon Head” by Lazzari et al., published in
IEEE Transactions on Magnetics,
Vol. 34, No. 4, July, 1998, discloses a slider of triangular shape. The triangularly shaped slider is fabricated by cutting a silicon wafer in three directions. The triangular shape reduces the unused surface of the slider. However, an unwanted process deviation may lead to slider non-triangularity, and there is still the potential for damage of the recording media as the edges of the slider make contact with the disk.
There is a need, therefore, for an improved slider that overcomes the above difficulties.
SUMMARY
A recording head slider having a trapezoidal shape is described according to an exemplary embodiment of the present invention. The slider is made of silicon and has a first parallel surface larger than a second parallel surface. The first parallel surface is the surface upon which the recording head is fabricated. The first parallel surface of the slider also includes rounded corners.
The slider further may include longitudinal, through or partially-through holes within its body to reduce the mass of the slider. A pattern of these through or partially-through holes may be used as a slider identification system, as well, in which a reader may identify the slider origin based on the pattern of the holes at the surface. The slider may also include longitudinal grooves, having an arbitrary cross-section, along its slanted side surfaces. These grooves produce non-planar structures along the length of the slider body, allowing more convenient part handling and location. Furthermore, these grooves may also form the basis of a slider identification system, in which the presence or absence of a groove or protrusion along the sides or top of the slider allows its identification with respect to position location within the wafer and/or the wafer identity.
The trapezoidal silicon slider of the exemplary embodiment is incorporated in a recording device. The recording device includes a trapezoidal silicon slider mounted on the suspension, which is suspended above a recording medium. The slider is mounted on the suspension at its first slanted side surface such that a trailing end of the slider, which is the first parallel surface of the slider, is larger than its leading end, which is the second parallel surface of the slider. Therefore, a built-in positive pitch of about 0.6 degree is generated. The leading end of the slider has a rounded leading edge that is advantageous for preventing the damage of a magnetic recording disk when the leading edge contacts the disk during operation. A second slanted side surface opposite the first slanted side surface is an air bearing surface of the slider in the recording device. The longitudinal edges at this air bearing surface are also rounded during the slider fabrication process.
The trapezoidal slider of the exemplary embodiment is fabricated using a commercial deep reactive ion etching (DRIE) technique. A silicon substrate is first provided, upon which the recording head is fabricated using thin film processing. Photoresist masks are then deposited onto a top surface of the silicon substrate. The photoresist masks are patterned with round corners, through holes, and grooves at the sides, producing a slider having a first parallel surface with rounded corners, longitudinal through holes or partially-through holes within the body, and the longitudinal grooves along its slanted side surfaces. Partially-through holes may be generated in the slider body by choosing a maximum diameter or dimension of the pattern in the photoresist used to define the etched area. If this dimension is below a certain level, dependent on the thickness of the wafer to be etched, the etching process is terminated at a point above the bottom of the wafer. Thus, somewhat conical holes may be generated which merely reduce the sli
Bunch Richard
Crawforth Linden J.
Razouk Anthony A.
Reiley Timothy C.
Hitachi Global Storage Technologies - Netherlands B.V.
Klimowicz William
Lumen Intellectual Property Services Inc.
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