Abstract: Apparatus for detecting defects in a substrate comprises a laser for providing a laser beam, and a bi-cell photodiode comprising two cells. Circuitry coupled to the bi-cell photodiode provides a signal equal to (L−R)/(L+R), where L and R equal the signal strengths of the signals provided by the left and right photodiode cells, respectively. The photodiode is biased so that it exhibits reduced capacitance, and can provide increased output signal bandwidth.

Abstract: A method for making a magnetic disk comprises forming first and second protective carbon layers on a magnetic layer. The first protective carbon layer is predominantly SP3 carbon. The second protective carbon layer comprises about 50% or less SP3 carbon. The second protective carbon layer is very thin, e.g. between 0.1 and 1.0 nm thick. A lubricant layer (e.g. a perfluoropolyether lubricant) is applied to the second protective carbon layer. The second protective carbon layer facilitates improved cooperation between lubricant and the disk.

Abstract: Substrate inspection apparatus in accordance with the invention comprises optics for reflecting a laser beam off of a substrate and a detector for detecting the reflected laser beam. If a defect is present at the point where the laser reflects off the substrate, the laser will be deflected at an angle. Circuitry coupled to the detector generates a first signal that provides a measure of the extent to which the laser beam is deflected. (This signal is a measure of the slope of the defect walls.) An integrator receives that signal, and generates a second signal that is the integral of the first signal. The second signal is a measure of the height of the defect. The first and second signals provide a measure of the types of defects present on the substrate, and are used to determine whether the substrate is acceptable or should be rejected. In accordance with a second embodiment of the invention, laser beams are reflected off both the top and bottom surfaces of the substrate and detected by detectors.

Abstract: A first disk carrier constructed in accordance with the invention is substantially circular, and has a size and shape such that it can be placed in an opening in a second, larger disk carrier. In one embodiment, the second, large disk carrier is a conventional disk carrier, e.g. used to hold a substrate during a magnetic disk manufacturing process. The first disk carrier is circular, and has a diameter equal (or substantially equal) to common substrates currently being manufactured. Therefore, the first disk carrier fits in and can be held by the second disk carrier. The first disk carrier has one or more openings for holding one or more substrates that have a diameter substantially less than the diameter of the opening of the second disk carrier.

Abstract: In this invention, an ultra thin layer of CoCr alloy nucleation layer is sputtered at an extremely low deposition rate above a predominantly (200) oriented Cr film followed by a CoCrPt based alloy sputtered film at higher rates and moderate temperatures. This structure creates a media which has very high Hc, and excellent PW50, low noise and excellent low TNLD values. By using this technique, the CoCrPt magnetic film achieves excellent in-plane crystallographic orientation, and high Hc is achieved with minimal amount of Pt addition to the magnetic film. The method allows very fine grain structure of cobalt to be formed which contributes to good signal to noise ratio. A fine grain structure combined with chromium segregation between the grains improve the signal to noise ratio even more. A high degree of in-plane c-axis orientation is achieved in the cobalt layer which provides very high hysteresis loop squareness which helps to improve the OW and TNLD.

Abstract: A method for making a credit card (or other type of data storing card) comprising a magnetic strip includes the step of depositing a magnetic recording layer on a substrate, cutting the substrate into strips, and mounting the strips onto the credit card. In one embodiment, the strips comprise glass that is sufficiently thin to be bendable. The magnetic recording layer is sputtered onto the glass using a high temperature sputtering apparatus. In another embodiment, the substrate is a metal foil. The data recording capacity of the magnetic strip is greater than that which can be achieved by using particulate media.

Abstract: A method for improving corrosion resistance while maximizing magnetic performance of a magnetic disk employed in data storage applications. The invention includes providing a substrate and forming a first layer above the substrate, the first layer having a first degree of abrasion resistance. The invention includes forming a second layer such as a Ni-containing layer above the first layer, the Ni-containing layer having a second degree of abrasion resistance lower than the first degree of abrasion resistance. The invention further includes forming grooves in the Ni-containing layer.

Abstract: An apparatus and method write data to a storage medium, and subsequently automatically refresh the data to avoid loss of the data due to spontaneous thermal degradation. The apparatus and method may check whether an indicator (also called “refresh indicator”) if saved contemporaneous with writing of the data satisfies a predetermined condition indicating that the data needs to be refreshed. If so, a “refresh” operation is performed, wherein the to-be-refreshed data is read from and written back to the same storage medium. The refresh indicator can be any parameter that indicates a need to refresh the data prior to occurrence of one or more soft errors. In one example, the apparatus and method read the data back contemporaneous with writing of the data, and measure an amplitude of a readback signal and store, as the refresh indicator, a predetermined fraction (e.g. half) of the measured value (i.e., a threshold number).

Abstract: A method for marking the defective side of a magnetic disk comprises the step of applying a set of laser pulses to the defective side to form a mark that is visible to the naked eye. Thus, disk drive manufacturers can readily see whether one side of the disk is defective, and if so, which side of the disk is defective. Thus, the disk drive manufacturer can assemble a disk drive so as to use the functional side of the disk. The laser marks are formed on the disk without generating particulate contamination.

Abstract: A method for manufacturing a magnetic disk comprises the acts of a) applying a laser beam to at least a portion of a silica-containing substrate, thereby forming a set of bumps or ridges; b) etching the substrate to remove the ridges and form a set of valleys where the ridges were previously formed; and c) depositing an underlayer, a magnetic layer, and a protective overcoat on the substrate. A lubricant layer is then formed on the disk. The valleys formed in the substrate reduce stiction exhibited by the magnetic disk. However, the valleys do not interfere with the fly height of a read-write head used in conjunction with the magnetic disk.

Abstract: A disk drive having spacers to compensate for disk warpage is described. The spacers are positioned on opposite sides of a disk with each spacer contacting the disk a different radial position relative to the center of the disk. The offset contact areas result in displaced moments on the disk, with respect to each other, when the spacers are clamped to the disk. The moments generated by the clamped spacers provide a torque on a warped disk to improve its flatness.

Abstract: A method for making magnetic disks comprises the steps of: applying a protective layer of material on a sheet of glass; b) cutting the sheet of glass into glass squares; c) stacking the glass squares; d) removing a circular core from the stack of glass squares, thereby defining the inner diameter of the glass substrates being formed; e) using a cutting annulus to cut through the stack of glass squares, thereby forming a stack of glass disks; f) subjecting the stack of glass disks to an edge polishing process to round the corners of the glass disks both at the inner and outer diameters; h) unstacking the glass disks; i) removing the protective layers from the glass disks; j) subjecting the glass disks to a chemical strengthening step; and k) sputtering an underlayer, magnetic layer and protective overcoat onto the glass substrate to thereby form a magnetic disk.

Abstract: A method for texturing a substrate comprises rotating the substrate while applying laser pulses thereto. Of importance, the rotational velocity of the substrate is varied during texturing to change the spacing of the resulting laser bumps in accordance with a periodic function. This helps reduce or eliminate vibration in a read-write head after the substrate is formed into a magnetic disk, and the magnetic disk is in use.

Abstract: A method in accordance with our invention for providing texture bumps on a substrate comprises the step of forming elliptical ridge-shaped bumps on the substrate. In one embodiment, substrate is used in the manufacture of a magnetic disk used in a disk drive. The elliptical bumps cause less vibration of the read-write head than circular bumps. The elliptical bumps also provide reduced friction between the disk and a read-write head during use.

Abstract: A method for polishing a glass or glass ceramic substrate comprises the step of using a slurry comprising both diamond and CeO2 particles. We have discovered that the presence of both diamond and CeO2 particles permits one to polish at a high glass removal rate, and concurrently, to leave a texture on the surface of the glass substrate.

Abstract: A slurry in accordance with the invention comprises CeO2 polishing particles and sodium polyacrylate in an aqueous solution. This slurry is used to polish a glass or glass ceramic substrate. I have discovered that adding sodium polyacrylate to a CeO2 slurry improves the polishing rate without causing a major negative impact on the slurry stability or redispersibility. In addition, the addition of the sodium polyacrylate does not cause a great deal of foaming. This polishing process can be used to prepare substrates for the manufacture of magnetic disks.

Abstract: A method for drying workpieces in accordance with our invention includes the step of immersing the workpieces in a liquid, holding the workpieces with a first holding mechanism, slowly draining the liquid from the container until a first portion of the workpieces is exposed and dried, holding the workpieces with a second holding means at the first portion, and draining the remainder of the liquid from the container. Because of this, a drying portion of the workpiece is not held by a wet holding mechanism.

Abstract: A novel slurry for polishing and a method of polishing using a slurry is disclosed. The slurry may include a colloidal silica abrasive in an aqueous solution. The slurry further includes a chelating agent that is believed to remove adsorbed ions from the surface of the layer being polished. The method may be used to polish a surface comprising, for example nickel and the chelating agent may be, for example, ammonium oxalate.

Abstract: A method of manufacturing a magnetic disk includes the steps of depositing a sublayer, a Cr layer and a Co based magnetic layer on a substrate. The sublayer causes the Cr crystals to avoid growing with a predominantly (200) orientation. Because of this the magnetic layer will be isotropic in the film plane and independent of any texture or scratch marks in the substrate.

Abstract: A Co-Pt based magnetic alloy which has been doped with a relatively high amount of nitrogen, e.g., or above 1 at. % is obtained having high coercivity, for example in the range of 1400 Oe or above, and an increased signal-to-noise ratio as compared to the same Co-Pt based alloy which has not been doped with nitrogen. The alloy is vacuum deposited, for example, by sputtering, and the nitrogen may be introduced from the sputtering gas or from the sputtering target.