Patents by Inventor Haiwen Xi

Haiwen Xi 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: 20110149642
    Abstract: Apparatus and associated method for writing data to a non-volatile memory cell, such as spin-torque transfer random access memory (STRAM). In accordance with some embodiments, a resistive sense element (RSE) has a heat assist region, magnetic tunneling junction (MTJ), and pinned region. When a first logical state is written to the MTJ with a spin polarized current, the pinned and heat assist regions each have a substantially zero net magnetic moment. When a second logical state is written to the MTJ with a static magnetic field, the pinned region has a substantially zero net magnetic moment and the heat assist region has a non-zero net magnetic moment.
    Type: Application
    Filed: March 3, 2011
    Publication date: June 23, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Xiaohua Lou, Haiwen Xi, Michael Xuefei Tang
  • Patent number: 7966581
    Abstract: Method and apparatus for constructing and operating an integrated circuit in an electronic device. In some embodiments, a generic service layer is integrated in a three dimensional integrated circuit and tested using a testing pattern stored in a non-volatile memory. The generic service layer is reconfigured to a permanent non-testing functional component of the integrated circuit.
    Type: Grant
    Filed: October 16, 2008
    Date of Patent: June 21, 2011
    Assignee: Seagate Technology LLC
    Inventors: Yiran Chen, Dadi Setiadi, Hai Li, Haiwen Xi, Hongyue Liu
  • Patent number: 7961509
    Abstract: A spin-transfer torque memory apparatus and self-reference read and write assist schemes are described. One method of self-reference reading a spin-transfer torque memory unit includes applying a first read current through a magnetic tunnel junction data cell and forming a first bit line read voltage. A magnetic field is applied through the free magnetic layer the forming a magnetic field modified magnetic tunnel junction data cell. Then a second read current is applied thorough the magnetic field modified magnetic tunnel junction data cell forming a second bit line read voltage and compared with the first bit line read voltage to determine whether the first resistance state of the magnetic tunnel junction data cell was a high resistance state or low resistance state. Methods of applying a destabilizing magnetic field to the MTJ and then writing the desired resistance state are also disclosed.
    Type: Grant
    Filed: October 13, 2010
    Date of Patent: June 14, 2011
    Assignee: Seagate Technology LLC
    Inventors: Wenzhong Zhu, Yiran Chen, Xiaobin Wang, Zheng Gao, Haiwen Xi, Dimitar V. Dimitrov
  • Publication number: 20110134682
    Abstract: Variable write and read methods for resistance random access memory (RRAM) are disclosed. The methods include initializing a write sequence and verifying the resistance state of the RRAM cell. If a write pulse is needed, then two or more write pulses are applied through the RRAM cell to write the desired data state to the RRAM cell. Each subsequent write pulse has substantially the same or greater write pulse duration. Subsequent write pulses are applied to the RRAM cell until the RRAM cell is in the desired data state or until a predetermined number of write pulses have been applied to the RRAM cell. A read method is also disclosed where subsequent read pulses are applied through the RRAM cell until the read is successful or until a predetermined number of read pulses have been applied to the RRAM cell.
    Type: Application
    Filed: February 16, 2011
    Publication date: June 9, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Hongyue Liu, Xiaobin Wang, Yong Lu, Yiran Chen, Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Hai Li
  • Publication number: 20110134688
    Abstract: An apparatus and method for compensating for asymmetric write current in a non-volatile unit cell. The unit cell comprises a switching device and an asymmetric resistive sense element (RSE), such as an asymmetric resistive random access memory (RRAM) element or an asymmetric spin-torque transfer random access memory (STRAM) element. The RSE is physically oriented within the unit cell relative to the switching device such that a hard direction for programming the RSE is aligned with an easy direction of programming the unit cell, and an easy direction for programming the RSE is aligned with a hard direction for programming the unit cell.
    Type: Application
    Filed: January 28, 2011
    Publication date: June 9, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Wenzhong Zhu, Yong Lu, Xiaobin Wang, Yiran Chen, Alan Xuguang Wang, Xiaohua Lou, Haiwen Xi
  • Patent number: 7952917
    Abstract: Variable write and read methods for resistance random access memory (RRAM) are disclosed. The methods include initializing a write sequence and verifying the resistance state of the RRAM cell. If a write pulse is needed, then two or more write pulses are applied through the RRAM cell to write the desired data state to the RRAM cell. Each subsequent write pulse has substantially the same or greater write pulse duration. Subsequent write pulses are applied to the RRAM cell until the RRAM cell is in the desired data state or until a predetermined number of write pulses have been applied to the RRAM cell. A read method is also disclosed where subsequent read pulses are applied through the RRAM cell until the read is successful or until a predetermined number of read pulses have been applied to the RRAM cell.
    Type: Grant
    Filed: June 4, 2010
    Date of Patent: May 31, 2011
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Hongyue Liu, Xiaobin Wang, Yong Lu, Yiran Chen, Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Hai Li
  • Publication number: 20110121418
    Abstract: A free ferromagnetic data storage layer of an MRAM cell is coupled to a free ferromagnetic stabilization layer, which stabilization layer is directly electrically coupled to a contact electrode, on one side, and is separated from the free ferromagnetic data storage layer, on an opposite side, by a spacer layer. The spacer layer provides for the coupling between the two free layers, which coupling is one of: a ferromagnetic coupling and an antiferromagnetic coupling.
    Type: Application
    Filed: January 27, 2011
    Publication date: May 26, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Kaizhong Gao, Dimitar V. Dimitrov, Song S. Xue
  • Publication number: 20110116303
    Abstract: A magnetic memory device includes a magnetic tunnel junction having a free magnetic layer having a magnetization orientation that is switchable between a high resistance state magnetization orientation and a low resistance state magnetization orientation and a memristor solid state element electrically coupled to the magnetic tunnel junction. The memristor has a device response that is an integrated voltage versus an integrated current.
    Type: Application
    Filed: January 24, 2011
    Publication date: May 19, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Xiaobin Wang, Yiran Chen, Alan Wang, Haiwen Xi, Wenzhong Zhu, Hai Li, Hongyue Liu
  • Patent number: 7940600
    Abstract: A method and apparatus for stray magnetic field compensation in a non-volatile memory cell, such as a spin-torque transfer random access memory (STRAM). In some embodiments, a first tunneling barrier is coupled to a reference structure that has a perpendicular anisotropy and a first magnetization direction. A recording structure that has a perpendicular anisotropy is coupled to the first tunneling barrier and a nonmagnetic spacer layer. A compensation layer that has a perpendicular anisotropy and a second magnetization direction in substantial opposition to the first magnetization direction is coupled to the nonmagnetic spacer layer. Further, the memory cell is programmable to a selected resistance state with application of a current to the recording structure.
    Type: Grant
    Filed: December 2, 2008
    Date of Patent: May 10, 2011
    Assignee: Seagate Technology LLC
    Inventors: Dimitar Dimitrov, Olle Gunnar Heinonen, Dexin Wang, Haiwen Xi
  • Patent number: 7939188
    Abstract: A magnetic stack having a free layer having a switchable magnetization orientation, a reference layer having a pinned magnetization orientation, and a barrier layer therebetween. The stack includes an annular antiferromagnetic pinning layer electrically isolated from the free layer and in physical contact with the reference layer. In some embodiments, the reference layer is larger than the free layer.
    Type: Grant
    Filed: July 13, 2009
    Date of Patent: May 10, 2011
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Antoine Khoueir, Brian Lee, Pat Ryan, Michael Tang, Insik Jin, Paul E. Anderson
  • Patent number: 7936598
    Abstract: A magnetic memory cell having a ferromagnetic free layer and a ferromagnetic pinned reference layer, each having an out-of-plane magnetic anisotropy and an out-of-plane magnetization orientation and switchable by spin torque. The cell includes a ferromagnetic assist layer proximate the free layer, the assist layer having a low magnetic anisotropy less than about 500 Oe. The assist layer may have in-plane or out-of-plane anisotropy.
    Type: Grant
    Filed: April 28, 2009
    Date of Patent: May 3, 2011
    Assignee: Seagate Technology
    Inventors: Yuankai Zheng, Zheng Gao, Wonjoon Jung, Xuebing Feng, Xiaohua Lou, Haiwen Xi
  • Patent number: 7935435
    Abstract: A magnetic tunnel junction cell having a free layer, a ferromagnetic pinned layer, and a barrier layer therebetween. The free layer has a central ferromagnetic portion and a stabilizing portion radially proximate the central ferromagnetic portion. The construction can be used for both in-plane magnetic memory cells where the magnetization orientation of the magnetic layer is in the stack film plane and out-of-plane magnetic memory cells where the magnetization orientation of the magnetic layer is out of the stack film plane, e.g., perpendicular to the stack plane.
    Type: Grant
    Filed: September 19, 2008
    Date of Patent: May 3, 2011
    Assignee: Seagate Technology LLC
    Inventors: Kaizhong Gao, Haiwen Xi
  • Patent number: 7936592
    Abstract: A method and apparatus for writing data to a non-volatile memory cell, such as a spin-torque transfer random access memory (STRAM) memory cell. In some embodiments, a selected resistive state is written to a magnetic tunneling structure by applying a succession of indeterminate write pulses thereto until the selected resistive state is verified.
    Type: Grant
    Filed: February 3, 2009
    Date of Patent: May 3, 2011
    Assignee: Seagate Technology LLC
    Inventors: Xiaobin Wang, Yong Lu, Haiwen Xi, Yuankai Zheng, Yiran Chen, Harry Hongyue Liu, Dimitar Dimitrov, Wei Tan, Brian Seungwhan Lee
  • Patent number: 7936585
    Abstract: A non-volatile memory cell and associated method is disclosed that includes a non-ohmic selection layer. In accordance with some embodiments, a non-volatile memory cell consists of a resistive sense element (RSE) coupled to a non-ohmic selection layer. The selection layer is configured to transition from a first resistive state to a second resistive state in response to a current greater than or equal to a predetermined threshold.
    Type: Grant
    Filed: July 13, 2009
    Date of Patent: May 3, 2011
    Assignee: Seagate Technology LLC
    Inventors: Wei Tian, Insik Jin, Venugopalan Vaithyanathan, Haiwen Xi, Michael Xuefei Tang, Brian Lee
  • Patent number: 7933146
    Abstract: Electronic devices that include (i) a magnetization controlling structure; (ii) a tunnel barrier structure; and (iii) a magnetization controllable structure including: a first polarizing layer; and a first stabilizing layer, wherein the tunnel barrier structure is between the magnetization controlling structure and the magnetization controlling structure and the first polarizing layer is between the first stabilizing layer and the tunnel barrier structure, wherein the electronic device has two stable overall magnetic configurations, and wherein a first unipolar current applied to the electronic device will cause the orientation of the magnetization controlling structure to reverse its orientation and a second unipolar current applied to the electronic device will cause the magnetization controllable structure to switch its magnetization in order to obtain one of the two stable overall magnetic configurations, wherein the second unipolar current has an amplitude that is less than the first unipolar current.
    Type: Grant
    Filed: March 31, 2009
    Date of Patent: April 26, 2011
    Assignee: Seagate Technology LLC
    Inventors: Dimitar V. Dimitrov, Olle Gunnar Heinonen, Yiran Chen, Haiwen Xi, Xiaohua Lou
  • Patent number: 7933137
    Abstract: Non-volatile magnetic random access memory (MRAM) devices that include magnetic flip-flop structures that include a magnetization controlling structure; a first tunnel barrier structure; and a magnetization controllable structure that includes a first polarizing layer; and a first stabilizing layer, wherein the first tunnel barrier structure is between the magnetization controllable structure and the magnetization controlling structure and the first polarizing layer is between the first stabilizing layer and the first tunnel barrier structure, wherein the magnetic flip-flop device has two stable overall magnetic configurations, and wherein a first unipolar current applied to the device will cause the orientation of the magnetization controlling structure to reverse its orientation and a second unipolar current applied to the electronic device will cause the magnetization controllable structure to switch its magnetization so that the device reaches one of the two stable overall magnetic configurations, wherein
    Type: Grant
    Filed: March 31, 2009
    Date of Patent: April 26, 2011
    Assignee: Seagate Teachnology LLC
    Inventors: Dimitar V. Dimitrov, Olle Gunnar Heinonen, Yiran Chen, Haiwen Xi, Xiaohua Lou
  • Publication number: 20110089510
    Abstract: A magnetic tunnel junction cell having a free layer, a ferromagnetic pinned layer, and a barrier layer therebetween. The free layer has a central ferromagnetic portion and a stabilizing portion radially proximate the central ferromagnetic portion. The construction can be used for both in-plane magnetic memory cells where the magnetization orientation of the magnetic layer is in the stack film plane and out-of-plane magnetic memory cells where the magnetization orientation of the magnetic layer is out of the stack film plane, e.g., perpendicular to the stack plane.
    Type: Application
    Filed: December 23, 2010
    Publication date: April 21, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Kaizhong Gao, Haiwen Xi
  • Publication number: 20110090733
    Abstract: A memory unit includes a giant magnetoresistance cell electrically coupled between a write bit line and a write source line. The giant magnetoresistance cell includes a free magnetic layer separated from a first pinned magnetic layer by a first non-magnetic electrically conducting layer. A magnetic tunnel junction data cell is electrically coupled between a read bit line and a read source line. The magnetic tunnel junction data cell includes the free magnetic layer separated from a second pinned magnetic layer by an oxide barrier layer. A write current passes through the giant magnetoresistance cell to switche the giant magnetoresistance cell between a high resistance state and a low resistance state. The magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by magnetostatic coupling with the giant magnetoresistance cell, and be read by a read current passing though the magnetic tunnel junction data cell.
    Type: Application
    Filed: December 21, 2010
    Publication date: April 21, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Hongyue Liu, Michael Xuefei Tang, Antoine Khoueir, Song S. Xue
  • Publication number: 20110075471
    Abstract: An apparatus and method for enhancing read and write sense margin in a memory cell having a resistive sense element (RSE), such as but not limited to a resistive random access memory (RRAM) element or a spin-torque transfer random access memory (STRAM) element. The RSE has a hard programming direction and an easy programming direction. A write current is applied in either the hard programming direction or the easy programming direction to set the RSE to a selected programmed state. A read circuit subsequently passes a read sense current through the cell in the hard programming direction to sense the selected programmed state of the cell.
    Type: Application
    Filed: December 6, 2010
    Publication date: March 31, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Wenzhong Zhu, Hai Li, Yiran Chen, Xiaobin Wang, Henry Huang, Haiwen Xi
  • Publication number: 20110069537
    Abstract: The present invention relates to a memory cell including a first reference layer having a first magnetization with a first magnetization direction and a second reference layer having a second magnetization with a second magnetization direction substantially perpendicular to the first magnetization direction. A storage layer is disposed between the first reference layer and second reference layer and has a third magnetization direction about 45° from the first magnetization direction and about 135° from the second magnetization direction when the memory cell is in a first data state, and a fourth magnetization direction opposite the third magnetization direction when the memory cell is in a second data state.
    Type: Application
    Filed: December 1, 2010
    Publication date: March 24, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Kaizhong Gao, Haiwen Xi, Yiming Shi, Song S. Xue, Sining Mao