Abstract: A process for fabricating sliders with one or more sacrificial structures (extensions) that facilitate lapping to create the air-bearing surface (ABS) is described. Prior to separating individual sliders from a wafer, a mask of material that is not removable by deep reactive ion etching (DRIE) is patterned on the surface of the sliders. The mask outlines a sacrificial extension around portions of the magnetic transducer elements that are nearest the predetermined plane which will become the ABS. The sacrificial extension makes the surface of the slider which will be lapped non-planar. The sacrificial extension extends below the predetermined ABS plane. When the sliders are individually separated by DRIE, the shape of the mask including the sacrificial extension is projected down into and along the slider body. In one embodiment, additional guide rails are disposed along the outer edges of the slider to facilitate maintaining slider symmetry during the lapping process.

Abstract: A method of influencing variations in composition of thin films is described. The elemental plasma field distribution in sputtering systems is manipulated by generating a nonuniform electric field along a surface of the substrate to alter the composition by differentially re-sputtering the target elements. The nonuniform electric field is applied by one or more electrodes in contact with a conductive surface or by using an RF bias signal. The nonuniform electric field is used to modulate the kinetic energy of the ions generated in the plasma which strike the thin film's surface. Since the kinetic energy and the mass of the sputtering gas ions and neutrals affect the re-sputtering rate, the nonuniform electric field differentially affects the elements being deposited according to mass. By applying varying electric potentials at a plurality of points on a conductive surface of a substrate, the electric field across the surface of the substrate can be modulated in a variety of patterns.

Abstract: A laser based inspection tool (LIT) for inspecting planar surfaces is described. In a preferred embodiment the LIT can simultaneously inspect both planar surfaces of disks for use in disk drives. In one embodiment of the invention, the incident beam is directed onto the surface to be inspected at an angle slightly offset from perpendicular so that the reflected beam is physically separated from the incident beam. The reflected beam is routed to a detector which converts the intensity of the reflected into an analog signal. The analog signal is sampled and digitized to generate pixel data stored in a buffer. Various analyses are performed on the data including calculating a rate of change in the pixel data. If the rate of change in the pixel data exceeds a selected threshold that indicates a possible defect if it occurs in the data area of the disk.

Abstract: A magnetic transducer with a bilayer pole piece in which a first layer of material forms the body of the pole piece and a second layer forms the pole tip after milling is disclosed, along with a disk drive using the transducer. The bilayer pole piece is used in a method to improve the determination of the optimum stopping point for the ion milling using the optically observable process of the gap layer and P1 tip layer being milled off of the P1 protection layer forming a gradually disappearing halo. The process of making the head proceeds conventionally through plating of the P1 layer which in applicant's head is the layer which forms the body of P1. The process of the invention deposits a P1 protection layer and then uses a photo lift-off technique to form a void in the P1 protection layer where the gap and the P1 and P2 tips will be formed, i.e., the zero throat region.

Abstract: A tunnel junction sensor according to the invention replaces the prior art free layer with a free layer structure which allows a wider range of magnetoresistive materials to be used. The preferred free layer structure of the invention includes a negative magnetostriction layer which allows use of magnetoresistive materials which otherwise have unacceptably high magnetostriction values. The materials and thicknesses of the layers are selected to result in a total magnetostriction near zero even though magnetoresistive material with high magnetostriction is included. The preferred embodiment includes a softening layer of material such as selected compositions of nickel-iron which maintain the desired magnetic softness of the free layer structure and have a magnetostriction constant near zero.

Abstract: A method and system are disclosed to provide a defect map structure that can increase the throughput of a recording apparatus when the recording apparatus accesses a data recording medium. A defect register method according to the present invention includes the steps of detecting initial defective sectors, generating a primary defect map (PDM) where each absolute block address of initial defective sectors (D.ABA) is individually registered, discriminating a series of defective sectors consisting of a plurality of initial defective sectors with continuous D.ABA, which exist in the same track (tracks having the same cylinder identification number CYL and head identification number HED) from the individual resister PDM, and generating a PDM, where this series of defective sectors is registered in a batch, by registering a first absolute block address of the series of defective sectors (D.ABA.ST), and defective sector length (number of defective sectors D.LE) of the series of defective sectors.

Abstract: A method and apparatus to provide a retract circuit that can correspond to the tendency toward miniaturization and low supply voltage. When drive supply voltage Vcc is applied, a retract circuit charges a retract condenser Cr with boosted voltage Vup, equal to three times Vcc, generated by a booster circuit. Then, if the drive supply voltage Vcc is cut off and a VCM driver stops, the retract circuit detects power-off with a power OFF sense circuit, and provides retract delay time by a retract delay circuit. Furthermore, when the retract delay time elapses after the drive power supply is turned off, the retract driver switches the switching circuits on, discharges the retract condenser, charged at the boosted voltage, supplies discharge current to a voice coil, and retracts the head assembly.

Abstract: A magnetic transducer (head) according to the invention includes a free layer structure comprising two free layers exchange coupled across a thin spacer structure of comprising two spacer layers of nonmagnetic material separated by a ferromagnetic nano-oxide layer (NOL). The spacer layers prevent the NOL from unnecessarily hardening the free layer(s). The spacer layers are preferably copper or copper oxide. The spacer layers preserve the NOL's property of specular scattering of conduction electrons which tends to increase the magnetoresistive response. A free layer structure including the exchange coupling spacer structure of the invention can be used in a dual spin valve configuration, but is also useful in a single spin valve configuration. The free layer of the invention is useful in conduction in-plane (CIP), as well as, conduction perpendicular to the plane (CPP) devices.

Abstract: A disk storage device is disclosed for avoiding the instantaneous performance degradation as much as possible, and a method for processing a defective sector in such a disk storage device. There is executed a predetermined check related to a function of the disk storage device, preferably at least one of a read test, a write servo test, or a write test, when the disk storage device is in a waiting state where the disk storage device has no access from a host. The read test and write servo test are used to search for a defective sector on a disk and reassign the defective sector. The write test is used to indicate an abnormal condition of a head. Furthermore, the disk storage device includes a detector for detecting the waiting state, and a check logic for executing a predetermined check.

Abstract: The present invention concerns at least an antiferromagnetic layer, which is in direct contact with a ferromagnetic layer for inducing an exchange bias in the ferromagnetic layer. Thus, the ferromagnetic layer is pinned by the antiferromagnetic layer, also referred to as the pinning layer. The antiferromagnetic or pinning layer comprises a compound from the group of orthoferrites, which show a variety of advantages. For example, these antiferromagnets can have a Néel temperature TN ranging from at least 623 K to 740 K depending on the compounds, and they can display a weak ferromagnetic moment. Therefore, a magnetic device comprising the mentioned structure can be used properly in an environment of a high operating temperature. The compound can be described by the formula RFe1−xTMxO3with R a rare earth element or Yttrium, and TM a transition metal which can be one element of the groups IB to VIII.

Abstract: A laser based inspection tool (LIT) for inspecting planar surfaces is described. In a preferred embodiment the LIT can simultaneously inspect both planar surfaces of disks for use in disk drives. In an embodiment of the invention, light reflected from the surface at an angle slightly offset from perpendicular is routed through a telecentric lens to a detector which converts the intensity of the reflected beam into an analog signal. The analog signal is sampled and digitized to generate pixel data. A data acquisition system sequentially stores the pixel data in a buffer. A median filter and derivative analysis can be applied to the pixel data to detect deviations indicating defects. An optional calibration system periodically reflects the scanning beam back to a detector to form a reference signal for use in absolute reflectivity measurements.

Abstract: The improved process according to the invention prepares samples for subsequent imaging by directing the FIB beam so that its incident angle is not parallel to the planar boundaries between the materials with different etch rates. This nonparallel alignment has the effect of evening out the etch rate, since most of the key beamlets cut more than one type of material. SEM images of the resulting samples are easier to interpret than those produced by the prior art since the obscuring effect of curtaining is reduced. This allows greater accuracy of measurement from the image obtained by an SEM. A method according to a preferred embodiment of the invention is used to prepare a pole piece tip of a magnetic transducer so that the bottom width may be more accurately measured.

Abstract: An inspection system using laser light directed at an off-axis parabolic mirror which focuses the beam on the surface being inspected and also serves as the collector for scattered and specular light returned from the surface is described. Specular and scattered light returned from the surface onto the parabolic mirror is divided into appropriate fields and directed onto detectors. In the preferred embodiment a polarized laser is used in conjunction with a polarizing beam splitter and a quarter-wave plate to route the reflected beam to a detector while allowing the original beam to be directed through the same optics. The parabolic mirror and selected additional components may be commonly mounted on a translatable stage which is moved along a radius of the disk when the optical inspection is being performed. Other components of the system such as the laser can remain in a fixed position.

Abstract: A thin film magnetic media structure comprising a pre-seed layer CrTi is disclosed. The CrTi pre-seed layer presents an amorphous or nanocrystalline structure. The preferred seed layer is RuAl. The use of the CrTi/RuAl bilayer structure provides superior adhesion to the substrate and resistance to scratching, as well as, excellent coercivity and signal-to-noise ratio (SNR) and reduced cost over the prior art.

Abstract: A overcoat layer of TiSixNy for use on a magnetic thin film disk is disclosed. The overcoat of the invention has high hardness, provides corrosion protection and has low surface energy which reduces contaminant attraction. The TiSixNy film is conductive and, therefore, reduces the deleterious effects of tribocharging.

Abstract: Method and apparatus to correct an error of read-out data from a data storage medium, particularly a bit shift error, is described. The correction apparatus includes a gray bit detection circuit which flags bits with a phase shift exceeding a threshold and determines whether the previous or next bit cell has a smaller phase error. An RLL error detection circuit and a table containing valid bit combinations may be used in combination with the gray bit detector to correct errors on-the-fly without degrading performance. An advantage of the invention is that it allows correction of errors without regard to conventional ECC and its maximum number of errors.

Abstract: An apparatus and method for detecting and marking delamination defects on thin film disks are disclosed. The apparatus includes a read/write (R/W) head and a burnishing head mounted on separate arms that access the disk while spinning on the test stand. The controller uses the R/W head to perform an initial magnetic test of selected areas on the disk to establish an initial defect map. The burnish head is then flown over the surface for an extended time to accelerate and open up the latent delamination defects by impacting protruding material. The R/W head is then used to perform a second magnetic test which is compared against the first test to identify the delamination defects which have been developed by the burnishing. The delamination defects are then marked with a magnetic pattern which aids in optically locating the defect during subsequent failure analysis.

Abstract: A sensor for measuring magnetostriction of and/or magnetic thin film is constructed by depositing a thin film nonferromagnetic electrically insulating layer followed by a thin film layer of a sensor material which is piezoresistive and nonferromagnetic. The insulating and the piezoresistive film can be etched into an appropriate pattern and orientation to provide sensitivity to strain in the magnetic film. The magnetostrictive strain in the magnetic film is induced by a known magnetic field which produces a corresponding strain in the piezoresistive film which can be measured as a change in the electrical resistance which can be detected by external probes or other measuring means. The measurement of the magnetostriction can be performed as a part of the manufacturing process for wafers with a plurality of thin film magnetic heads thereon and does not require that the wafers be removed to a laboratory.

Abstract: A thin film structure comprising a protective layer structure having at least two different compositions of carbon and nitrogen with the surface of the protective layer having the lowest nitrogen content is disclosed. The protective layer structure of the invention is preferably used over the magnetic material in a thin film magnetic disk. In the protective layer structure of the invention, the durability of a relatively high nitrogen content CNx material is improved by the addition of a surface sublayer of CNx with a relatively low nitrogen concentration. The resulting protective layer structure provides superior durability to either of the thin film compositions used alone achieving a synergistic result. The protective layer structure of the invention has the additional benefit of decreasing the polar surface energy and therefore, improving the corrosion resistance of the film structure.

Abstract: An antiferromagnetically coupled layer structure for magnetic recording wherein the top ferromagnetic structure is a bilayer structure including a relatively thin first sublayer of ferromagnetic material in contact with the coupling/spacer layer. The first sublayer has a higher magnetic moment than the second sublayer. The layer structure of the invention results improved manufacturability and improved performance. A preferred embodiment of a layer structure according to the invention includes: a bottom ferromagnetic layer preferably of CoCr; an antiferromagnetic coupling/spacer layer preferably of Ru; and a top ferromagnetic structure including a thin first sublayer of material preferably of CoCr, CoCrB or CoPtCrB, and a thicker second sublayer of material preferably of CoPtCrB with a lower moment than the first sublayer.