Patents by Inventor Hua-Ching Tong

Hua-Ching Tong has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7110289
    Abstract: In a method and system for reducing power consumed by a magnetic memory, magnetic memory cells are coupled to a bit line and are associated with a plurality of digit lines. A bit line current is provided in the bit line. Digit currents are provided in parallel in the digit lines at substantially the same time as the bit line current. The digit and bit line currents allow the magnetic memory cells to be written to a plurality of states in parallel.
    Type: Grant
    Filed: March 31, 2004
    Date of Patent: September 19, 2006
    Assignees: Western Digital (Fremont), Inc., STMicroelectronics S.R.L.
    Inventors: Kyusik Sin, Hugh Craig Hiner, Xizeng (Stone) Shi, William D. Jensen, Hua-Ching Tong, Matthew R Gibbons, Roberto Bez, Giulio Casagrande, Paolo Cappeletti, Marco Pasotti
  • Patent number: 7007372
    Abstract: An inductive write element is disclosed for use in a magnetic data recording system. The write element provides increased data rate and data density capabilities through improved magnetic flux flow through the element. The write element includes a magnetic yoke constructed of first and second magnetic poles. The first pole includes a pedestal constructed of a high magnetic moment (high Bsat) material, which is preferably FeRhN nanocrystalline films with lamination layers of CoZrCr. The second pole includes a thin inner layer of high Bsat material (also preferably FeRhN nanocrystalline films with lamination layers of CoZrCr), the remainder being constructed of a magnetic material capable of being electroplated, such as a Ni—Fe alloy. An electrically conductive coil passes through the yoke between the first and second poles to induce a magnetic flux in the yoke when an electrical current is caused to flow through the coil.
    Type: Grant
    Filed: September 5, 2003
    Date of Patent: March 7, 2006
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Hua-Ching Tong, Lei Wang, Xizeng Shi
  • Patent number: 6888184
    Abstract: A magnetic memory fabricated on a semiconductor substrate is disclosed. The method and system include a plurality of magnetic tunneling junctions and a plurality of shields for magnetically shielding the plurality of magnetic tunneling junctions. Each of the plurality of magnetic tunneling junctions includes a first ferromagnetic layer, a second ferromagnetic layer and an insulating layer between the first ferromagnetic layer and the second ferromagnetic layer. At least a portion of the plurality of shields have a high moment and a high permeability and are conductive. The plurality of shields are electrically isolated from the plurality of magnetic tunneling junctions. The plurality of magnetic tunneling junctions are between the plurality of shields.
    Type: Grant
    Filed: February 11, 2002
    Date of Patent: May 3, 2005
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Xizeng Shi, Matthew Gibbons, Hua-Ching Tong, Kyusik Sin
  • Patent number: 6873547
    Abstract: A magnetic memory is disclosed. The magnetic memory includes a first magnetic tunneling junction and a reference magnetic tunneling junction. The first magnetic tunneling junction includes a first ferromagnetic layer, a second ferromagnetic layer and a first insulating layer between the first ferromagnetic layer and the second ferromagnetic layer. The reference magnetic tunneling junction includes a third ferromagnetic layer, a fourth ferromagnetic layer and a second insulating layer between the third ferromagnetic layer and the fourth ferromagnetic layer. The magnetic memory also includes means for comparing a first output of the first magnetic tunneling junction with a reference output of the reference magnetic tunneling junction.
    Type: Grant
    Filed: February 22, 2002
    Date of Patent: March 29, 2005
    Assignee: Read Rite Corporation
    Inventors: Xizeng(Stone) Shi, Hua-Ching Tong, Aric K. Menon
  • Patent number: 6747301
    Abstract: A tunneling barrier for a spin dependent tunneling (SDT) device is disclosed that includes a plurality of ferromagnetic atoms disposed in a substantially homogenous layer. The presence of such atoms in the tunneling barrier is believed to increase a magnetoresistance or &Dgr;R/R response, improving the signal and the signal to noise ratio. Such an increase &Dgr;R/R response also offers the possibility of decreasing an area of the tunnel barrier layer. Decreasing the area of the tunnel barrier layer can afford improvements in resolution of devices such as MR sensors and increased density of devices such as of MRAM cells.
    Type: Grant
    Filed: February 6, 2002
    Date of Patent: June 8, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Hugh Craig Hiner, Kyusik Sin, Shin Funada, Xizeng Shi, Hua-Ching Tong
  • Publication number: 20040075958
    Abstract: A magnetoresistive (MR) device includes a synthetic antiferromagnetic (AFM) layer having an Fe/FeSi/Fe construction. A first Fe layer of the synthetic AFM layer has a magnetization substantially in a first direction, while a second Fe layer of the synthetic AFM layer has a magnetization substantially in a second direction that is substantially antiparallel to the first direction. The magnetoresistive device can be a spin valve in which a first surface of the synthetic AFM layer is adjacent to a pinning layer, and a second surface of the synthetic AFM layer is adjacent to a spacer layer. Further, the spin valve includes a free layer that overlies the spacer, thereby being separated from the synthetic AFM layer by the spacer. The pinning layer, synthetic AFM layer, spacer, and free layer can be bounded by a first shield and a second shield to provide magnetic shielding of the spin valve sensor.
    Type: Application
    Filed: October 14, 2003
    Publication date: April 22, 2004
    Applicant: Western Digital (Fremont)
    Inventors: Chih-Huang Lai, Zhupei Shi, Hua-Ching Tong, Robert E. Rottmayer, Charles W. Miller
  • Patent number: 6661625
    Abstract: A thin film read/write head with a high performance read section that includes a spin-dependent tunneling sensor composed of a new low resistance metal oxide tunneling barrier material, such as chromium oxide (CrxOy) or niobium oxide (NbOz). The chromium oxide material (CrxOy) can be, for example: Cr3O4, Cr2O3, CrO2, CrO3, Cr5O12, Cr6O15, other stoichiometry, or any combination thereof. The niobium oxide (NbOz) can be, for example: NbO, NbO2, Nb2O5, Nb2O3, Nb12O29, Nb11O27, other stoichiometry, or any combination thereof. The chromium oxide and the niobium oxide material provides a very low sensor resistance with an acceptable magnetoresistance ratio, which will enable the fabrication of high density read sensors, and thus read heads with high data transfer rate.
    Type: Grant
    Filed: February 20, 2001
    Date of Patent: December 9, 2003
    Inventors: Kyusik Sin, Ming Mao, Hua-Ching Tong, Chester Xiaowen Chien
  • Patent number: 6650503
    Abstract: An inductive write element for use with a magnetic data recording and retrieval system is provided. The write element includes a magnetic yoke having an electrically conductive coil passing there through. The yoke is constructed of first and second magnetic poles, and performance of the write element is improved by the inclusion of a very thin pedestal of a high magnetic moment material on the first pole in the pole tip region. Further performance gains are realized by providing a tapered edge on the pedestal to facilitate magnetic flux flow through the pedestal.
    Type: Grant
    Filed: June 13, 2002
    Date of Patent: November 18, 2003
    Assignee: Read-Rite Corporation
    Inventors: Yingjian Chen, Ron Barr, Hua-Ching Tong, Stone Shi, Kyusik Sin
  • Patent number: 6639291
    Abstract: A tunneling barrier for a spin dependent tunneling (SDT) device is disclosed that includes a plurality of ferromagnetic particles. The presence of such particles in the tunneling barrier has been found to increase a magnetoresistance or &Dgr;R/R response, improving the signal and the signal to noise ratio. Such an increased &Dgr;R/R response also offers the possibility of decreasing an area of the tunnel barrier layer and/or increasing a thickness of the tunnel barrier layer. Decreasing the area of the tunnel barrier layer can afford improvements in resolution of devices such as MR sensors and increased density of devices such as of MRAM cells. Increasing the thickness of the tunnel barrier can afford improvements in manufacturing such as increased yield.
    Type: Grant
    Filed: February 6, 2002
    Date of Patent: October 28, 2003
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kyusik Sin, Shin Funada, Hugh Craig Hiner, Hua-Ching Tong, Xizeng Shi
  • Patent number: 6633464
    Abstract: A magnetoresistive (MR) device includes a synthetic antiferromagnetic (AFM) layer having an Fe/FeSi/Fe construction. A first Fe layer of the synthetic AFM layer has a magnetization substantially in a first direction, while a second Fe layer of the synthetic AFM layer has a magnetization substantially in a second direction that is substantially antiparallel to the first direction. The magnetoresistive device can be a spin valve in which a first surface of the synthetic AFM layer is adjacent to a pinning layer, and a second surface of the synthetic AFM layer is adjacent to a spacer layer. Further, the spin valve includes a free layer that overlies the spacer, thereby being separated from the synthetic AFM layer by the spacer. The pinning layer, synthetic AFM layer, spacer, and free layer can be bounded by a first shield and a second shield to provide magnetic shielding of the spin valve sensor.
    Type: Grant
    Filed: December 9, 1998
    Date of Patent: October 14, 2003
    Assignee: Read-Rite Corporation
    Inventors: Chih-Huang Lai, Zhupei Shi, Hua-Ching Tong, Robert E. Rottmayer, Charles W. Miller
  • Patent number: 6618223
    Abstract: An inductive write element is disclosed for use in a magnetic data recording system. The write element provides increased data rate and data density capabilities through improved magnetic flux flow through the element. The write element includes a magnetic yoke constructed of first and second magnetic poles. The first pole includes a pedestal constructed of a high magnetic moment (high Bsat) material, which is preferably FeRhN nanocrystalline films with lamination layers of CoZrCr. The second pole includes a thin inner layer of high Bsat material (also preferably FeRhN nanocrystalline films with lamination layers of CoZrCr), the remainder being constructed of a magnetic material capable of being electroplated, such as a Ni—Fe alloy. An electrically conductive coil passes through the yoke between the first and second poles to induce a magnetic flux in the yoke when an electrical current is caused to flow through the coil.
    Type: Grant
    Filed: July 18, 2000
    Date of Patent: September 9, 2003
    Assignee: Read-Rite Corporation
    Inventors: Yingjian Chen, Hua-Ching Tong, Lei Wang, Xizeng Shi
  • Patent number: 6468436
    Abstract: A system and method for providing a head for reading data is disclosed. The method and system include providing a magnetoresistive element and providing a flux guide having a high resistivity. The magnetoresistive element has an end. The flux guide also has an end. The end of the flux guide is adjacent to the end of the magnetoresistive element.
    Type: Grant
    Filed: July 12, 2000
    Date of Patent: October 22, 2002
    Assignee: Read-Rite Corporation
    Inventors: Xizeng Shi, Hua-Ching Tong, Ming Zhao, Francis Liu
  • Patent number: 6459552
    Abstract: A thin film magnetic head employs pole tips members which are coplanar in a plane across the write gap to produce a written track whose width is determined by the thickness of the pole tip members. The coplanar write structure may be combined with a multilayer read sensor disposed in the write gap to produce a narrow trackwidth thin film magnetic head having both write and read capabilities.
    Type: Grant
    Filed: March 20, 2000
    Date of Patent: October 1, 2002
    Inventors: Francis H. Liu, Hua-Ching Tong, Samuel W. Yuan
  • Publication number: 20020114113
    Abstract: A magnetoresistive (MR) read sensor fabricated on a substrate includes a ferromagnetic layer that is exchange coupled with an antiferromagnetic layer made of a defined composition of iridium manganese. A tantalum layer is used so that the exchange field and coercivity do not change with variations in annealing temperature. The antiferromagnetic layer is formed with a material composition of IrxMn100-x wherein x is in the range of 15<x>23. In an embodiment of a spin valve structure, the tantalum layer is disposed over the substrate and the antiferromagnetic layer is in direct contact with a pinned ferromagnetic layer. In another embodiment, the IrMn layer is formed over a soft active layer. In a third embodiment using exchange pinning, spaced IrMn regions are formed over the active MR layer to define the sensor track width.
    Type: Application
    Filed: March 28, 2002
    Publication date: August 22, 2002
    Inventors: Marcos M. Lederman, Daniel A. Nepela, Hua-Ching Tong
  • Patent number: 6430806
    Abstract: An inductive write element for use with a magnetic data recording and retrieval system is provided. The write element includes a magnetic yoke having an electrically conductive coil passing there through. The yoke is constructed of first and second magnetic poles, and performance of the write element is improved by the inclusion of a very thin pedestal of a high magnetic moment material on the first pole in the pole tip region. Further performance gains are realized by providing a tapered edge on the pedestal to facilitate magnetic flux flow through the pedestal.
    Type: Grant
    Filed: June 23, 2000
    Date of Patent: August 13, 2002
    Assignee: Read-Rite Corporation
    Inventors: Yingjian Chen, Ron Barr, Hua-Ching Tong, Stone Shi, Kyusik Sin
  • Patent number: 6424507
    Abstract: A magnetoresistive read sensor fabricated on a substrate includes a ferromagnetic layer that is exchange coupled with an antiferromagnetic layer made of a defined composition of iridium manganese. A tantalum layer is used so that the exchange field and coercivity do not change with variations in annealing temperature. The antiferromagnetic layer is formed with a material composition of Irx Mn100-x, wherein x is in the range of 15<x>23. In an embodiment of a spin valve structure, the tantalum layer is disposed over the substrate and the antiferromagnetic layer is in direct contact with a pinned ferromagnetic layer. In another embodiment, the IrMn layer is formed over a soft active layer. In a third embodiment using exchange pinning, spaced IrMn regions are formed over the active magnetoresistive layer to define the sensor track width.
    Type: Grant
    Filed: April 3, 2000
    Date of Patent: July 23, 2002
    Assignee: Read-Rite Corporation
    Inventors: Marcos M. Lederman, Daniel A. Nepela, Hua-Ching Tong
  • Patent number: 6392850
    Abstract: Magnetic transducers are formed with common magnetic exchange layers capable of providing assertive and complementary signals. The transducers include an assertive transducer portion and a complementary transducer portion. Between the two transducer portions is a common bias portion which comprises an antiferromagnetic layer providing bias fields in different directions to the respective transducer portions. During normal operations, a current is directed into each of the transducer portions. The assertive transducer portion, being magnetically biased in one direction, generates a varying voltage as an assertive version of the electrical signal. The complementary transducer, being magnetically biased in another direction, generates another varying voltage as a complementary version of the electrical signal. In one embodiment, the transducer portions are implemented to operate as an anisotropic MR(AMR) sensor. In a second embodiment, the transducer portions operate as a giant MR(GMR) or spin valve sensor.
    Type: Grant
    Filed: October 19, 1998
    Date of Patent: May 21, 2002
    Assignee: Read-Rite Corporation
    Inventors: Hua-Ching Tong, Francis H. Liu, Minshen Tan, Robert Earl Rottmayer, Jian-Gang Zhu, Samuel W. Yuan
  • Patent number: 6351355
    Abstract: The present invention provides spin valve with a magnetic compensation field which couples to the pinned layer and counteracts sensing current induced magnetic field. The spin valve sensor of the present invention may be formed having a structure comprising: a free layer, a first spacer layer, a pinned layer, a pinning layer, a second spacer layer, and a compensation layer. The compensation layer may be formed of ferromagnetic material with its magnetization set so that the compensation field oriented in a reinforcing relationship with the magnetization of the pinned layer. Current through the compensation layer and the spacer layer may add to the compensation field. The spacer layer may be formed of a nonmagnetic material of sufficient thickness to prevent interaction between the pinning layer and the compensation layer while providing a sufficiently small distance to allow sufficient magnetic coupling to the pinned layer.
    Type: Grant
    Filed: February 9, 1999
    Date of Patent: February 26, 2002
    Assignee: Read-Rite Corporation
    Inventors: Tai Min, Hua-Ching Tong, Yiming Huai, Wengie Chen
  • Publication number: 20010040774
    Abstract: A method and system for providing a dual spin valve is disclosed. The dual spin valve is for reading data in a magnetic recording media. The method and system include providing a first pinned layer. The first pinned layer has a first magnetization. The method and system also include providing a CoFe free layer and providing a first nonmagnetic spacer layer. The first nonmagnetic spacer layer is between the first pinned layer and the CoFe free layer. The method and system also include providing a second pinned layer and a second nonmagnetic spacer layer. The second pinned layer has a second magnetization. The second nonmagnetic spacer layer is between the CoFe free layer and the second pinned layer.
    Type: Application
    Filed: August 18, 1999
    Publication date: November 15, 2001
    Applicant: Read-Rite Corporation
    Inventors: SHIN FUNADA, MING MAO, HUA-CHING TONG
  • Patent number: 6317297
    Abstract: A method and system for providing a magnetoresistive sensor is disclosed. The method and system include providing a first pinned layer, providing a first spacer layer above the first pinned layer, and providing a free layer above the first spacer layer. The method and system further include providing a second spacer layer above the free layer and providing a second pinned layer above the second spacer layer. The first pinned layer includes a first magnetic layer and a second magnetic layer separated by a first nonmagnetic layer. The first magnetic layer is antiferromagnetically coupled with the second magnetic layer. The second pinned layer includes a third magnetic layer and a fourth magnetic layer separated by a second nonmagnetic layer. The third magnetic layer is antiferromagnetically coupled with the fourth magnetic layer. The first pinned layer and the second pinned layer are pinned by a current carried by the magnetoresistive head during use.
    Type: Grant
    Filed: October 6, 1999
    Date of Patent: November 13, 2001
    Assignee: Read-Rite Corporation
    Inventors: Hua-Ching Tong, Xizeng Shi, Subrata Dey, Matthew Richard Gibbons