Patents by Inventor Xizeng Shi

Xizeng Shi 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).

  • Publication number: 20050276098
    Abstract: A method and system for providing a magnetic memory including magnetic memory cells associated with a word line segment is disclosed. The magnetic memory cell includes a magnetic storage device and an isolation device. The isolation device is coupled to the magnetic tunneling junction and with a combined word line for reading and writing to the magnetic memory cell. The magnetic storage device and the isolation device are configured such that no direct current path to ground exists during the writing to the magnetic memory cell. In one aspect, in a write mode, the combined word line associated with the word line segment and the word line segment are activated. In the read mode, at least a portion of the memory cells associated with the word line segment are selected using the combined word line.
    Type: Application
    Filed: June 9, 2004
    Publication date: December 15, 2005
    Inventors: Hsu Yang, Xizeng Shi, Po-Kang Wang, Bruce Yang
  • Publication number: 20050276100
    Abstract: A method and system for programming and reading a magnetic memory is disclosed. The magnetic memory includes a plurality of selectable word line segments and a plurality of magnetic storage cells corresponding to each word line segment. The method and system include reading the magnetic storage cells corresponding to a word line segment to determine a state of each magnetic storage cell. In one aspect, the method and system also include utilizing at least one storage for storing a state of each of the magnetic storage cells determined during a read operation made during a write operation. The method and system also include writing data to a portion of the magnetic cells corresponding to the word line segment after the reading. The method and system also include rewriting the state to each of a remaining portion of the magnetic storage cells corresponding to the word line segment at substantially the same time as the portion of the magnetic cells are written.
    Type: Application
    Filed: June 9, 2004
    Publication date: December 15, 2005
    Inventors: Hsu Yang, Xizeng Shi, Po-Kang Wang, Bruce Yang
  • Publication number: 20050219895
    Abstract: An MTJ MRAM cell element, whose free layer has a shape induced magnetic anisotropy, is formed between orthogonal word and bit lines. The bit line is a composite line which includes a high conductivity current carrying layer and a soft adjacent magnetic layer (SAL). During operation, the soft magnetic layer concentrates the magnetic field of the current and, due to its proximity to the free layer, it magnetically couples with the free layer to produce two magnetization states of greater and lesser stability. During switching, the layer is first placed in the less stable state by a word line current, so that a small bit line current can switch its magnetization direction. After switching, the state reverts to its more stable form as a result of magnetostatic interaction with the SAL, which prevents it from being accidentally rewritten when it is not actually selected and also provides stability against thermal agitation.
    Type: Application
    Filed: April 6, 2004
    Publication date: October 6, 2005
    Inventors: Yimin Guo, Po-Kang Wang, Xizeng Shi, Tai Min
  • Publication number: 20050180201
    Abstract: A method and system for programming a magnetic memory is disclosed. The method and system further include turning on a word line current and turning on a bit line current. The word line current is for generating at least one hard axis field. The bit line current is for generating at least one easy axis field. In one aspect, the method and system further include turning off the word line current and the bit line current such that a state of the at least one magnetic memory cell is repeatably obtained. In another aspect, the word line current is turned off after the bit line current is turned off.
    Type: Application
    Filed: June 3, 2004
    Publication date: August 18, 2005
    Inventors: Xizeng Shi, Son Le, Po-Kang Wang, Tai Min
  • Patent number: 6906894
    Abstract: A read/write head and method of making the same are used in a data storage system, such as a disk drive, for perpendicular magnetic recording of data. The head employs a two-layer pole design with a main pole made of sputtered high moment magnetic material, and an adjunct pole made of electroplated soft magnetic film. The main pole is used to write data onto the medium, and is formed over the write coil. The adjunct pole is substantially recessed from the air bearing surface and is formed over the main pole. The present head design significantly enhances the magnetic write field, and substantially reduces side-writing that result in accidental erasure of data in adjacent tracks on the magnetic recording medium.
    Type: Grant
    Filed: July 29, 2004
    Date of Patent: June 14, 2005
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Xiaozhong Dang, Francis H. Liu, Kroum Stoev, Hai Jiang, Yugang 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
  • Publication number: 20050048674
    Abstract: A method and system for providing a magnetic element and a magnetic memory using the magnetic element are disclosed. The magnetic memory includes a plurality of magnetic elements. The method and system include providing a plurality of layers and a passivation layer for each of the plurality of magnetic elements. A portion of the layers in the magnetic element includes at least one magnetic layer. The plurality of layers also has a top and a plurality of sides. The passivation layer covers at least a portion of the plurality of sides.
    Type: Application
    Filed: February 17, 2004
    Publication date: March 3, 2005
    Inventors: Xizeng Shi, Po-Kang Wang, Yimin Guo, Tai Min
  • Publication number: 20050007696
    Abstract: A read/write head and method of making the same are used in a data storage system, such as a disk drive, for perpendicular magnetic recording of data. The head employs a two-layer pole design with a main pole made of sputtered high moment magnetic material, and an adjunct pole made of electroplated soft magnetic film. The main pole is used to write data onto the medium, and is formed over the write coil. The adjunct pole is substantially recessed from the air bearing surface and is formed over the main pole. The present head design significantly enhances the magnetic write field, and substantially reduces side-writing that result in accidental erasure of data in adjacent tracks on the magnetic recording medium.
    Type: Application
    Filed: July 29, 2004
    Publication date: January 13, 2005
    Applicant: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Xiaozhong Dang, Francis Liu, Kroum Stoev, Hai Jiang, Yugang Wang, Xizeng Shi
  • Patent number: 6834010
    Abstract: An MRAM storage device includes temperature dependent current sources that adjust their outputs as temperature varies. Temperature dependent current sources include one or more diodes connected to a transistor. As temperature varies so does the voltage drop across the diodes. In addition, the MRAM data storage device includes at least one digit line, at least one bit line, and at least one MRAM cell disposed proximate to a junction of a digit line and a bit line. Each end of each digit line is connected to temperature dependent current sources and current sinks. One end of each bit line is connected to a temperature dependent current source while the other end of each bit line is connected to a current sink. Two logic signals R and D are used to activate a write operation and determine the direction of the write current in the digit line.
    Type: Grant
    Filed: December 18, 2003
    Date of Patent: December 21, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Qiuqun Qi, Xizeng Shi
  • Patent number: 6809899
    Abstract: Electromagnetic transducers are disclosed having write poles with a leading edge that is smaller than a trailing edge, which can reduce erroneous writing for perpendicular recording systems. The write poles may have a trapezoidal shape when viewed from a direction of an associated medium. The write poles may be incorporated in heads or sliders that also contain read elements such as magnetoresistive sensors, and may be employed with information storage systems such as disk drives.
    Type: Grant
    Filed: December 31, 2003
    Date of Patent: October 26, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Yugang Wang, Francis Liu, Xizeng Shi, Kyusik Sin, Hugh Craig Hiner
  • Patent number: 6803615
    Abstract: An MRAM cell includes a pinned layer, a free layer, and a bit line with a magnetic sheath. The magnetic sheath allows a magnetic field to circulate in a loop around the bit line. The looping magnetic field can couple with the magnetic field of the free layer for enhanced stability with respect to stray magnetic fields and elevated temperatures.
    Type: Grant
    Filed: December 14, 2001
    Date of Patent: October 12, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kyusik Sin, Xizeng Shi, Hugh Craig Hiner
  • Publication number: 20040191928
    Abstract: A method and system for providing magnetic memory cells in a magnetic memory is disclosed. The method and system include providing each magnetic memory element, providing a first write line and a second write line for each magnetic memory element. The magnetic memory element has a top portion and a bottom portion. The first write line is below the magnetic memory element and is electrically connected with the bottom portion of the magnetic memory element. The second write line is above the magnetic memory element. The second write line is electrically isolated from the magnetic memory element and oriented at an angle to the first write line. The magnetic memory cell allows for a simplified fabrication process, a reduced cell size, and an improved programming efficiency.
    Type: Application
    Filed: June 26, 2003
    Publication date: September 30, 2004
    Inventor: Xizeng Shi
  • Patent number: 6791793
    Abstract: A read/write head and method of making the same, are used in a data storage system, such as a disk drive, for perpendicular magnetic recording of data. The head employs a two-layer pole design with a main pole made of sputtered high moment magnetic material, and an adjunct pole made of electroplated soft magnetic film. The adjunct pole is substantially recessed from the air bearing surface. The present head design significantly enhances the magnetic write field, and substantially reduces side-writing that result in accidental erasure of data in adjacent tracks on the magnetic recording medium.
    Type: Grant
    Filed: September 14, 2001
    Date of Patent: September 14, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Xiaozhong Dang, Francis H. Liu, Kroum Stoev, Hai Jiang, Yugang Wang, Xizeng Shi
  • Patent number: 6785955
    Abstract: A method and system for providing a writer is disclosed. The method and system include providing a first pole, an insulator covering a portion of the first pole and a coil on the first insulator. The coil includes a plurality of turns. The method and system also include providing a second insulator covering the coil, providing a second pole on the second insulator and providing a write gap separating a portion of the first pole from a second portion of the second pole. A first portion of the second pole is coupled with the first pole. In one aspect, the method and system include providing a coil having a plurality of turns with a pitch of no more than 1.2 micrometers. In another aspect, the plurality of turns of the coil is provided using a hard mask layer on a photoresist layer. A portion of the hard mask layer and a portion of the photoresist layer define a plurality of spaces between the pluralities of turns of the coil. In another aspect, the writer is a pedestal defined zero throat writer.
    Type: Grant
    Filed: January 23, 2001
    Date of Patent: September 7, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Hugh Craig Hiner, Benjamin Chen, Xizeng Shi, Kyusik Sin
  • 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
  • Patent number: 6744608
    Abstract: A method and system for providing a tunneling magnetoresistive sensor is disclosed. The method and system include providing a pinned layer, a free layer and an insulating layer between the pinned and free layers. The pinned and free layers are ferromagnetic. The method and system also include providing a hard mask layer to be used in defining the sensor at the top of the tunneling magnetoresistive sensor. The method and system also include using the hard mask layer to define the tunneling magnetoresistive sensor. Thus, the pinned layer, the free layer and the insulating layer are capable of having a minimum dimension of less than 0.2 &mgr;m.
    Type: Grant
    Filed: May 14, 2002
    Date of Patent: June 1, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kyusik Sin, Kristian M. Bjelland, Benjamin Chen, Hugh C. Hiner, Xizeng Shi
  • Patent number: 6721138
    Abstract: An inductive transducer having first and second magnetic pedestals disposed between first and second magnetic pole layers and adjacent to a media-facing surface, the pedestals separated by a submicron, nonmagnetic gap. The first pedestal extends less than the second pedestal from the media-facing surface, defining a short throat height. The second pedestal extends further to provide sufficient area for stitching to the second pole layer. The stitching and the thickness provided by the pedestals allow plural coil layers to be disposed between the pole layers, and the second pedestal, as well as other features, can be defined by high-resolution photolithography. The two coil layers have lower resistance, lower inductance and allow the pole layers to be shorter, improving performance. All or part of either or both of the pedestals may be formed of high magnetic saturation material, further enhancing performance.
    Type: Grant
    Filed: October 24, 2001
    Date of Patent: April 13, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Yingjian Chen, Xizeng Shi, Hugh Craig Hiner, Zi-Wen Dong, Francis Liu, Matthew R. Gibbons, Joyce Anne Thompson, William D. Jensen, Chester Xiaowen Chien, Yugang Wang
  • Patent number: 6721203
    Abstract: A reference cell circuit for a magnetic tunnel junction MRAM includes a first magnetic tunnel junction device set to a low resistance state and a second magnetic tunnel junction device set to a high resistance state. A reference cell series unit includes the first magnetic tunnel junction device electrically coupled in series with the second magnetic tunnel junction device. The reference cell series unit further has a first end and a second end with the first end being electrically coupled to a first current source and the second end being electrically coupled to a current sink and a second current source.
    Type: Grant
    Filed: December 12, 2001
    Date of Patent: April 13, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Qiuqun Qi, Xizeng Shi, Matthew R. Gibbons
  • Patent number: 6713801
    Abstract: A method and system for providing a tunneling junction is disclosed. The method and system includes providing a free layer, a pinned layer, and a barrier between the free layer and the pinned layer. The free layer and the pinned layer are ferromagnetic. The barrier layer is an insulator. The magnetic tunneling junction is coupled to an &agr;-Ta lead.
    Type: Grant
    Filed: July 9, 2002
    Date of Patent: March 30, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Kyusik Sin, Hugh C. Hiner, Xizeng Shi
  • Patent number: 6707083
    Abstract: A method and system for providing a magnetic tunneling junction is disclosed. The method and system includes providing a free layer, a pinned layer, and a barrier between the free layer and the pinned layer. The free layer and the pinned layer are ferromagnetic. The barrier layer is an insulator. The magnetic tunneling junction is coupled to a bit line. The bit line includes a ferromagnetic liner and a nonmagnetic core. The nonmagnetic core includes a top, a bottom and sides. The ferromagnetic liner includes at least one tab and is adjacent to the sides and a portion of the bottom of the nonmagnetic core. The at least one tab is adjacent to the portion of the bottom of the nonmagnetic core.
    Type: Grant
    Filed: July 9, 2002
    Date of Patent: March 16, 2004
    Assignee: Western Digital (Fremont), Inc.
    Inventors: Hugh C. Hiner, Kyusik Sin, Matthew Gibbons, Xizeng Shi