Patents Represented by Attorney Leslie G. Murray
  • Patent number: 5696654
    Abstract: A dual element magnetoresistive (MR) sensor is disclosed comprising two MR elements separated by a high resistivity conductive spacer material. A layer of hard bias material, which abuts one of the MR elements at each of its track edges, has a magnetization times thickness value substantially matched to that of the one MR element to bias it in one longitudinal direction. An exchange bias layer biases the other MR element by exchange coupling in an opposite longitudinal direction to achieve magnetic stabilization between the MR elements. The exchange bias layer abuts the other MR element at each of its track edges and has a magnetization times thickness value substantially matched to that of the other MR element. Alternatively, the exchange bias layer extends from one track edge to an opposite track edge in continuous underlying or overlying contact with the other MR element.
    Type: Grant
    Filed: June 7, 1996
    Date of Patent: December 9, 1997
    Assignee: International Business Machines Corporation
    Inventors: Hardayal Singh Gill, Mustafa Pinarbasi
  • Patent number: 5686193
    Abstract: A layered magnetic structure with a seed layer on a substrate and a bulk layer on the seed layer. The seed layer is a gas-doped sendust layer with a thickness of 100-800 .ANG.. The bulk layer is sendust with a thickness of 0.3-10.0 .mu.m. The seed layer and the bulk layer have different weight compositions.
    Type: Grant
    Filed: January 30, 1996
    Date of Patent: November 11, 1997
    Assignee: International Business Machines Corporation
    Inventor: John David Westwood
  • Patent number: 5680281
    Abstract: A magnetoresistive (MR) sensor comprising a layer of ferromagnetic material forming an MR sensing element wherein the MR sensor is biased by utilizing only the MR stripe uniaxial anisotropy and the shape anisotropy of the active region of the sensing element. The active region of the MR element has a generally square geometry to provide the desired shape anisotropy. The MR sensor is biased at approximately 45 degrees by defining the magnetization at the four edges of the sense element active region utilizing its shape anisotropy and canting the magnetic easy axis at an appropriate angle during fabrication of the MR sensor. To minimize Barkhausen noise, a single magnetic domain configuration is achieved by reducing the sensor active region dimensions, i.e., stripe height and track width, to less than the characteristic domain wall thickness such that the formation of multiple magnetic domains is no longer energetically favorable.
    Type: Grant
    Filed: June 7, 1995
    Date of Patent: October 21, 1997
    Assignee: International Business Machines Corporation
    Inventors: Kenneth Ting-Yuan Kung, Po-Kang Wang
  • Patent number: 5664316
    Abstract: A magnetoresistive (MR) read transducer having passive end regions separated by a central active region in which an MR layer is formed over substantially only the central active region and in which a magnetic bias layers is formed in each passive end region. Each of the magnetic bias layers includes a layer of ferromagnetic material and a layer of antiferromagnetic material overlaying and in contact with the ferromagnetic layer to provide an exchange-coupled magnetic bias field. Each of the magnetic bias layers form an abutting junction having magnetic and electrically continuity with the MR layer to produce a longitudinal magnetic bias field in the transducer.
    Type: Grant
    Filed: May 10, 1995
    Date of Patent: September 9, 1997
    Assignee: International Business Machines Corporation
    Inventors: Mao-Min Chen, Robert Edward Fontana, Mohamad Towfik Krounbi, Kenneth Ting-Yuan Kung, James Hsi-Tang Lee, Jyh-Shiliey Jerry Lo, Ching Hwa Tsang, Po-Kang Wang
  • Patent number: 5666246
    Abstract: A magnetic storage system in which a magnetoresistive (MR) transducer utilizes a high coercivity magnetic material to produce a bias field for achieving higher signal output with low currents for narrow track width applications. Strips of high coercivity magnetic material contiguously contact opposite track-overlying edges of an MR layer. Each strip has a horizontal component of magnetization times its thickness that is at least equal to a horizontal component of magnetization of the MR layer times its thickness before the MR layer is biased by the strips, and each strip has its magnetization direction canted at an angle .phi. from its horizontal component. The MR layer is asymmetrically positioned between spaced magnetic shields and the MR layer is separated by a conductive nonmagnetic spacer layer from a shunt layer.
    Type: Grant
    Filed: May 4, 1995
    Date of Patent: September 9, 1997
    Assignee: International Business Machines Corporation
    Inventors: Hardayal Singh Gill, David Eugene Heim
  • Patent number: 5638237
    Abstract: In a magnetic read/write assembly, a removable fusible-link shorts the magnetoresistive (MR) sensor element to minimize electrical current through the MR sensing element during discharge of static electricity. Other magnetic head assembly elements such as the write coil and MR magnetic shields are also shorted using fusible-links. The fusible-link is removable during the assembly process. The existing terminal pads and wires are used to remove the fusible-link.
    Type: Grant
    Filed: August 25, 1995
    Date of Patent: June 10, 1997
    Assignee: International Business Machines Corporation
    Inventors: Peter B. Phipps, Erhard T. Schreck, Albert J. Wallash
  • Patent number: 5638235
    Abstract: A magnetic storage system in which a magnetoresistive (MR) transducer utilizes a high coercivity magnetic material to produce a bias field for achieving higher signal output with low currents for narrow track width applications. Strips of high coercivity magnetic material contiguously contact opposite track-overlying edges of an MR layer. Each strip has a horizontal component of magnetization times its thickness that is at least equal to a horizontal component of magnetization of the MR layer times its thickness before the MR layer is biased by the strips, and each strip has its magnetization direction canted at an angle .phi. from its horizontal component. The MR layer is asymmetrically positioned between spaced magnetic shields and the MR layer is separated by a conductive nonmagnetic spacer layer from a shunt layer.
    Type: Grant
    Filed: October 22, 1996
    Date of Patent: June 10, 1997
    Assignee: International Business Machines Corporation
    Inventors: Hardayal S. Gill, David E. Heim
  • Patent number: 5617277
    Abstract: A magnetic disk storage system with high linear resolution magnetoresistive (MR) head or heads comprising a dielectric substrate, a first magnetic shield, a first gap insulation layer, an MR stripe element, conductive leads, a second gap insulation layer, and a second magnetic shield. Back-fill layers of insulation material are deposited on the first gap insulation layer adjacent the MR element and/or on the second gap insulation layer in thicknesses substantially sufficient to at least in part replace insulation material removed during the various processing steps to ensure against short circuiting of the MR element.
    Type: Grant
    Filed: January 22, 1996
    Date of Patent: April 1, 1997
    Assignee: International Business Machines Corporation
    Inventors: Mao-Min Chen, Mohamad T. Krounbi
  • Patent number: 5614727
    Abstract: A thin film diode and method of fabrication having large current capability and low-turn on voltage is provided as a switching or protective device against electrostatic discharge in integrated devices such as magnetoresistive sensors and the like. A first semiconductor thin film layer of NiO.sub.x having p type properties is disposed on an arbitrary substrate, such as alumina, glass, silicon dioxide, silicon and the like. A second semiconducting layer of tin oxide or indium oxide or other transparent oxide is joined to the first layer to form a p/n junction. In one method of fabrication, the p/n junction is formed in a sputtering process under a partial oxygen pressure to control the stoichiometry of the films. Gold and Gold Indium contacts are attached to the films to provide electrical contacts. The device is enclosed in a protective coating and connected in parallel with an electronic device subject to electrostatic discharge.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: March 25, 1997
    Assignee: International Business Machines Corporation
    Inventors: Daniele Mauri, Wen Y. Lee, Cherngye Hwang, Glen Garfunkel
  • Patent number: 5604073
    Abstract: In a bi-layer lift-off process, the adhesion characteristics of a PMGI release layer are substantially improved by the use of ortho-hydroxy substituted 4-phenylazo compounds (azo dyes), a class of nonactinic dyes, as an adhesion promoter additive. These azo dyes, due to their chemical structure, exhibit selective binding to various metals by acting as a chelating ligand to the metal surface. Formulations of a specific azo dye, Sudan Orange G, at concentrations from 0.25 to 1.0 percent (by weight) in PMGI exhibits no loss of adhesion at prebake temperature in the range of 120 to 160 degrees C.
    Type: Grant
    Filed: May 30, 1995
    Date of Patent: February 18, 1997
    Assignee: International Business Machines Corporation
    Inventors: Mohamad T. Krounbi, Alfred F. Renaldo, Douglas J. Werner
  • Patent number: 5603156
    Abstract: A method of lapping the air bearing surface of a magnetoresistive head which minimizes the likelihood of interelement shorts at the air bearing surface is described. In a final, linear lapping phase, the air bearing surface is lapped back and forth parallel to the longitudinal axis of the head elements in an oscillatory path across a stationary lapping surface. Any scratches or smears of the elements will be along the length of the elements rather than transverse to the elements. Any transverse scratches or smears occurring in earlier lapping phases will be removed during the linear lapping phase.
    Type: Grant
    Filed: December 16, 1994
    Date of Patent: February 18, 1997
    Assignee: International Business Machines Corporation
    Inventors: Robert G. Biskeborn, Carol Y. Inouye, David J. Seagle, Albert J. Wallash, Robert O. Barr, Glen A. Garfunkel, Sanford J. Lewis
  • Patent number: 5600880
    Abstract: In the manufacture of a thin-film magnetic head having a vertical gap, auxiliary support is provided at the ends of a gap wall prior to formation of the magnetic poles. In a preferred embodiment, a pit is defined in a substrate and a release layer is deposited on the substrate followed by a layer of alumina. A recess is then etched through the alumina layer to the release layer in the pit. A partial layer of polymer or metal is deposited with a vertical edge across the median of the pit and recess. A layer of nonmagnetic wall material such as silicon oxide is deposited which after etching leaves a wall against the vertical edge of the partial layer. After removal of the partial layer, a vertical wall extends transversely across the recess and pit with the ends of the wall anchored and supported at the recess sidewalls. Alternatively, a pedestal may be provided in the recess to support each end of the wall. The magnetic poles are then formed simultaneously on either side of the wall.
    Type: Grant
    Filed: May 12, 1995
    Date of Patent: February 11, 1997
    Assignee: International Business Machines Corporation
    Inventors: Hugo A. E. Santini, Clinton D. Snyder
  • Patent number: 5600519
    Abstract: A thin film magnetic head in which the width of the first and second magnetic yoke layers between the zero throat point and the yoke flare point is progressively widened to equalize the flux density over this length so that the whole length reaches saturation simultaneously at a single current. Consequently, the field at the gap at the air bearing surface increases insignificantly once saturation of this length occurs, and the write field is then constant for currents above the saturation value.
    Type: Grant
    Filed: March 6, 1995
    Date of Patent: February 4, 1997
    Assignee: International Business Machines Corporation
    Inventors: David E. Heim, Mason L. Williams, III
  • Patent number: 5598308
    Abstract: A magnetoresistive (MR) sensor comprising a layered structure having at least one trilayer comprising a first and a second thin film ferromagnetic layers separated by and in interfacial contact with a third thin film non-metallic magnetic layer. A fourth thin film layer of material is within the first ferromagnetic layer, and the fourth layer has a thickness between a fraction of a monolayer and several monolayers and is located at predetermined distance from the interface between the first and third layers. A current flow is produced through the MR sensor and variations in resistivity of the MR sensor produced by rotation of the magnetization in one or both of the ferromagnetic layers is sensed as a function of the magnetic field being sensed.
    Type: Grant
    Filed: August 15, 1994
    Date of Patent: January 28, 1997
    Assignee: International Business Machines Corporation
    Inventors: Bernard Dieny, Bruce A. Gurney, Stuart S. P. Parkin, Ian L. Sanders, Virgil S. Speriosu, Dennis R. Wilhoit
  • Patent number: 5591533
    Abstract: In a magnetoresistive read transducer, a material which is inert with respect to the soft film magnetic biasing layer is formed at the surface of the substrate prior to soft film deposition. In a preferred embodiment of the present invention, a substrate surface layer of metal such as Cr or Ta is used. These metals have high resistivity due to partial oxidation when deposited on the substrate to reduce shunting of sensing current through the magnetoresistive layer, and further acts as a barrier to protect the soft film from substrate interface contamination. The surface layer also acts as a seed layer to set the soft film magnetization orientation in a well-defined direction therefore reducing magnetic instability.
    Type: Grant
    Filed: June 1, 1995
    Date of Patent: January 7, 1997
    Assignee: International Business Machines Corporation
    Inventor: Mustafa Pinarbasi
  • Patent number: 5588199
    Abstract: A method of lapping magnetoresistive (MR) heads individually which provides an MR element having a desired height with minimized skew is described. During fabrication of the MR head, one or more shunt resistors are formed between the edge of the MR element and the head air bearing surface. The shunt resistors are electrically connected at each end to extensions of the MR electrical leads and connected to the MR element and to each other at points between the ends forming a resistor network. During lapping of the MR head, the resistance of the resistor network is measured by an Ohmmeter connected between the MR element leads. As portions of the shunt resistors are ground away, the changes in the measured resistance of the resistor network are used to monitor and control any skew in the lapping process.
    Type: Grant
    Filed: November 14, 1994
    Date of Patent: December 31, 1996
    Assignee: International Business Machines Corporation
    Inventors: Mohamad T. Krounbi, Hin P. E. Lee, David J. Seagle
  • Patent number: 5582860
    Abstract: A method for producing a magnetic structure, such as a thin film magnetic head, in which the magnetic and electrical characteristics of magnetic material are tailored to produce magnetic and electrical characteristics in selected localized areas of the magnetic material. In a specific embodiment, the structure comprises a layer of magnetic material having an overlayer and an underlayer, and the magnetic characteristics of the material are modified by rapid thermal annealing.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: December 10, 1996
    Assignee: International Business Machines Corporation
    Inventors: Robert E. Fontana, Jr., Frances A. Houle, Ching H. Tsang
  • Patent number: 5576908
    Abstract: In a disk drive actuator head stack assembly, magnetic transducers including magnetoresistive (MR) read heads are connected to a current source and configured to provide an MR sensor current to each MR head wherein the direction of current flow for the MR sensor current in each MR head is the same relative to the actuator for all of the MR heads in the actuator head stack. This configuration allows all of the MR heads in the head stack assembly to be initialized simultaneously by applying a homogeneous magnetic field to the head stack assembly, thus providing the capability of initializing the MR heads at the actuator or disk drive level rather than requiring that the MR heads be initialized individually.
    Type: Grant
    Filed: April 1, 1994
    Date of Patent: November 19, 1996
    Assignee: International Business Machines Corporation
    Inventors: Glen A. Garfunkel, Mike P. Salo, Akihiko Aoyagi, Hiroshi Yanagisawa, Hiroshima Terashima, Kenji Kuroki
  • Patent number: 5574605
    Abstract: A magnetoresistive read sensor based on the spin valve effect in which a component of the read element resistance varies as the cosine of the angle between the magnetization directions in two adjacent magnetic layers is described. The sensor read element includes two adjacent ferromagnetic layers separated by a nonmagnetic metallic layer. A layer of antiferromagnetic material is formed over one of the ferromagnetic layers to provide an exchange bias field which fixes or "pins" the magnetization direction in the one ferromagnetic layer. An interlayer of magnetically soft material is deposited between the ferromagnetic and antiferromagnetic layers separating the ferromagnetic layer from the antiferromagnetic layer and enhancing the exchange coupling, particularly in the instance where the ferromagnetic material is iron or an iron alloy.
    Type: Grant
    Filed: November 17, 1995
    Date of Patent: November 12, 1996
    Assignee: International Business Machines Corporation
    Inventors: Peter M. Baumgart, Bernard Dieny, Bruce A. Gurney, Virgil S. Speriosu, Dennis R. Wilhoit
  • Patent number: 5560097
    Abstract: An integral combination magnetic transducer and suspension assembly suitable for use in both contact recording and in winchester-type applications. A generally rectangular elongated flat suspension member includes a vertical-type inductive read/write transducer formed integrally with the suspension member and is embedded in one end of the suspension member. The vertical inductive transducer is suitable for vertical recording applications. The transducer vertical magnetic pole tip and magnetic yoke structure are formed at one end of the suspension member with the vertical pole tip extending to and exposed at an air bearing surface formed on the lower surface of a slider-shaped protrusion extending from the lower surface of the end of the suspension member. The integral transducer/suspension assembly can be adapted for either flying above the recording media or for use in continuous contact with the recording media. The air bearing surface is formed on the lower surface of a wear pad.
    Type: Grant
    Filed: March 17, 1995
    Date of Patent: October 1, 1996
    Assignee: International Business Machines Corporation
    Inventors: Christopher H. Bajhorek, Robert E. Fontana, Clint D. Snyder, David A. Thompson, Mason L. Williams, Celia E. Yeack-Scranton