Patents by Inventor Zhitao Diao

Zhitao Diao 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: 20110031569
    Abstract: A method and system for providing a magnetic element and a magnetic memory utilizing the magnetic element are described. The magnetic element is used in a magnetic device that includes a contact electrically coupled to the magnetic element. The method and system include providing pinned, nonmagnetic spacer, and free layers. The free layer has an out-of-plane demagnetization energy and a perpendicular magnetic anisotropy corresponding to a perpendicular anisotropy energy that is less than the out-of-plane demagnetization energy. The nonmagnetic spacer layer is between the pinned and free layers. The method and system also include providing a perpendicular capping layer adjoining the free layer and the contact. The perpendicular capping layer induces at least part of the perpendicular magnetic anisotropy in the free layer. The magnetic element is configured to allow the free layer to be switched between magnetic states when a write current is passed through the magnetic element.
    Type: Application
    Filed: May 7, 2010
    Publication date: February 10, 2011
    Applicant: GRANDIS, INC.
    Inventors: Steven M. Watts, Zhitao Diao, Xueti Tang
  • Publication number: 20110032644
    Abstract: A method and system for providing a magnetic element and a magnetic memory utilizing the magnetic element are described. The magnetic element is used in a magnetic device that includes a contact electrically coupled to the magnetic element. The method and system include providing pinned, nonmagnetic spacer, and free layers. The free layer has an out-of-plane demagnetization energy and a perpendicular magnetic anisotropy corresponding to a perpendicular anisotropy energy that is less than the out-of-plane demagnetization energy. The nonmagnetic spacer layer is between the pinned and free layers. The method and system also include providing a perpendicular capping layer adjoining the free layer and the contact. The perpendicular capping layer induces at least part of the perpendicular magnetic anisotropy in the free layer. The magnetic element is configured to allow the free layer to be switched between magnetic states when a write current is passed through the magnetic element.
    Type: Application
    Filed: August 10, 2009
    Publication date: February 10, 2011
    Applicant: GRANDIS, INC.
    Inventors: Steven M. Watts, Zhitao Diao, Xueti Tang
  • Patent number: 7859034
    Abstract: Magnetic multilayer structures, such as magnetic or magnetoresistive tunnel junctions (MTJs) and spin valves, having a magnetic biasing layer formed next to and magnetically coupled to the free ferromagnetic layer to achieve a desired stability against fluctuations caused by, e.g., thermal fluctuations and astray fields. Stable MTJ cells with low aspect ratios can be fabricated using CMOS processing for, e.g., high-density MRAM memory devices and other devices, using the magnetic biasing layer. Such multilayer structures can be programmed using spin transfer induced switching by driving a write current perpendicular to the layers to switch the magnetization of the free ferromagnetic layer.
    Type: Grant
    Filed: April 16, 2009
    Date of Patent: December 28, 2010
    Assignee: Grandis Inc.
    Inventors: Yiming Huai, Zhitao Diao, Eugene Youjun Chen
  • Patent number: 7851840
    Abstract: Devices having magnetic or magnetoresistive tunnel junctions (MTJS) have a multilayer insulator barrier layer to produce balanced write switching currents in the device circuitry, or to produce the magnetic devices with balanced critical spin currents required for spin torque transfer induced switching of the magnetization, or both for the MTJs under both the forward and reversed bias directions.
    Type: Grant
    Filed: September 13, 2006
    Date of Patent: December 14, 2010
    Assignee: Grandis Inc.
    Inventors: Zhitao Diao, Yiming Huai
  • Patent number: 7821087
    Abstract: A method and system for providing a magnetic element that can be used in a magnetic memory is disclosed. The magnetic element includes pinned, nonmagnetic spacer, and free layers. The spacer layer resides between the pinned and free layers. The free layer can be switched using spin transfer when a write current is passed through the magnetic element. The magnetic element may also include a barrier layer, a second pinned layer. Alternatively, second pinned and second spacer layers and a second free layer magnetostatically coupled to the free layer are included. In one aspect, the free layer(s) include ferromagnetic material(s) diluted with nonmagnetic material(s) and/or ferrimagnetically doped to provide low saturation magnetization(s).
    Type: Grant
    Filed: March 13, 2007
    Date of Patent: October 26, 2010
    Assignee: Grandis, Inc.
    Inventors: Paul Nguyen, Yiming Huai, Zhitao Diao, Frank Albert
  • Publication number: 20100247967
    Abstract: A method and system for providing a magnetic element are described. The method and system include providing a pinned layer, a barrier layer, and a free layer. The free layer includes a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer. The barrier layer resides between the pinned layer and the free layer and includes MgO. The first ferromagnetic layer resides between the barrier layer and the intermediate layer. The first ferromagnetic layer includes at least one of CoFeX and CoNiFeX, with X being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent. The first ferromagnetic layer is ferromagnetically coupled with the second ferromagnetic layer.
    Type: Application
    Filed: June 15, 2010
    Publication date: September 30, 2010
    Applicant: GRANDIS, INC.
    Inventors: Yiming Huai, Zhitao Diao, Eugene Youjun Chen
  • Patent number: 7777261
    Abstract: Magnetic multilayer structures, such as magnetic or magnetoresistive tunnel junctions (MTJs) and spin valves, having a magnetic biasing layer formed next to and magnetically coupled to the free ferromagnetic layer to achieve a desired stability against fluctuations caused by, e.g., thermal fluctuations and astray fields. Stable MTJ cells with low aspect ratios can be fabricated using CMOS processing for, e.g., high-density MRAM memory devices and other devices, using the magnetic biasing layer. Such multilayer structures can be programmed using spin transfer induced switching by driving a write current perpendicular to the layers.
    Type: Grant
    Filed: September 20, 2005
    Date of Patent: August 17, 2010
    Assignee: Grandis Inc.
    Inventors: Yiming Huai, Zhitao Diao, Eugene Youjun Chen
  • Patent number: 7760474
    Abstract: A method and system for providing a magnetic element are described. The method and system include providing a pinned layer, a barrier layer, and a free layer. The free layer includes a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first ferromagnetic layer and the second ferromagnetic layer. The barrier layer resides between the pinned layer and the free layer and includes MgO. The first ferromagnetic layer resides between the barrier layer and the intermediate layer. The first ferromagnetic layer includes at least one of CoFeX and CoNiFeX, with X being selected from the group of B, P, Si, Nb, Zr, Hf, Ta, Ti, and being greater than zero atomic percent and not more than thirty atomic percent. The first ferromagnetic layer is ferromagnetically coupled with the second ferromagnetic layer.
    Type: Grant
    Filed: July 14, 2006
    Date of Patent: July 20, 2010
    Assignee: Grandis, Inc.
    Inventors: Yiming Huai, Zhitao Diao, Eugene Youjun Chen
  • Patent number: 7738287
    Abstract: A method and system for providing a magnetic memory is disclosed. The method and system include providing a plurality of magnetic storage cells in an array, a plurality of bit lines, and at least one bias structure. Each of the plurality of magnetic storage cells includes at least one magnetic element having an easy axis and being programmable by at least one write current driven through the magnetic element. The plurality of bit lines corresponds to the plurality of magnetic storage cells. The at least one bias structure is magnetically coupled with the at least one magnetic element in each of the plurality of magnetic storage cells. The at least one bias structure provides a bias field in a direction greater than zero degrees and less than one hundred eighty degrees from the easy axis.
    Type: Grant
    Filed: March 27, 2007
    Date of Patent: June 15, 2010
    Assignee: Grandis, Inc.
    Inventors: Zhitao Diao, Lien-Chang Wang, Yiming Huai
  • Publication number: 20100072524
    Abstract: Magnetic multilayer structures, such as magnetic or magnetoresistive tunnel junctions (MTJs) and spin valves, having a magnetic biasing layer formed next to and magnetically coupled to the free ferromagnetic layer to achieve a desired stability against fluctuations caused by, e.g., thermal fluctuations and astray fields. Stable MTJ cells with low aspect ratios can be fabricated using CMOS processing for, e.g., high-density MRAM memory devices and other devices, using the magnetic biasing layer. Such multilayer structures can be programmed using spin transfer induced switching by driving a write current perpendicular to the layers to switch the magnetization of the free ferromagnetic layer.
    Type: Application
    Filed: April 16, 2009
    Publication date: March 25, 2010
    Inventors: Yiming Huai, Zhitao Diao, Eugene Youjun Chen
  • Patent number: 7663848
    Abstract: A method and system for providing a magnetic memory are described. The method and system include providing a plurality of magnetic storage cells. Each of the magnetic storage cells includes at least one magnetic element. The magnetic element(s) includes a pinned layer, a barrier layer that is a crystalline insulator and has a first crystalline orientation, and a free layer. The free layer includes a first ferromagnetic layer, a second ferromagnetic layer, and an intermediate layer between the first and second ferromagnetic layer. The barrier layer resides between the pinned and free layers. The first ferromagnetic layer resides between the barrier layer and the intermediate layer and is ferromagnetically coupled with the second ferromagnetic layer. The intermediate layer is configured such that the first ferromagnetic layer has the first crystalline orientation and the second ferromagnetic layer has a second crystalline orientation different from the first ferromagnetic layer.
    Type: Grant
    Filed: September 20, 2006
    Date of Patent: February 16, 2010
    Assignees: Grandis, Inc., Renesas Technology Corp
    Inventors: Yiming Huai, Zhitao Diao, Eugene Youjun Chen
  • Publication number: 20090050991
    Abstract: A magnetic device including a magnetic element is described. The magnetic element includes a fixed layer having a fixed layer magnetization, a spacer layer that is nonmagnetic, and a free layer having a free layer magnetization. The free layer is changeable due to spin transfer when a write current above a threshold is passed through the first free layer.
    Type: Application
    Filed: August 22, 2007
    Publication date: February 26, 2009
    Inventors: Hide Nagai, Zhitao Diao, Yiming Huai
  • Patent number: 7495303
    Abstract: A method and system include providing a single pinned layer, a free layer, and a spacer layer between the pinned and free layers. The spacer layer is nonmagnetic. The magnetic element is configured to allow the free layer to be switched due to spin transfer when a write current is passed through the magnetic element. The free layer is a simple free layer. In one aspect, the method and system include providing a spin engineered layer adjacent to the free layer. The spin engineered layer is configured to more strongly scatter majority electrons than minority electrons. In another aspect, at least one of the pinned, free, and spacer layers is a spin engineered layer having an internal spin engineered layer configured to more strongly scatter majority electrons than minority electrons. In this aspect, the magnetic element may include another pinned layer and a barrier layer between the free and pinned layers.
    Type: Grant
    Filed: January 29, 2007
    Date of Patent: February 24, 2009
    Assignee: Grandis, Inc.
    Inventors: Zhitao Diao, Yiming Huai, Thierry Valet, Paul P. Nguyen, Mahendra Pakala
  • Publication number: 20080273380
    Abstract: A method and system for providing a magnetic memory is disclosed. The method and system include providing a plurality of magnetic storage cells in an array, a plurality of bit lines, and at least one bias structure. Each of the plurality of magnetic storage cells includes at least one magnetic element having an easy axis and being programmable by at least one write current driven through the magnetic element. The plurality of bit lines corresponds to the plurality of magnetic storage cells. The at least one bias structure is magnetically coupled with the at least one magnetic element in each of the plurality of magnetic storage cells. The at least one bias structure provides a bias field in a direction greater than zero degrees and less than one hundred eighty degrees from the easy axis.
    Type: Application
    Filed: March 27, 2007
    Publication date: November 6, 2008
    Applicant: GRANDIS
    Inventors: Zhitao Diao, Lien-Chang Wang, Yiming Huai
  • Patent number: 7430135
    Abstract: Magnetic multilayer structures, such as magnetic or magnetoresistive tunnel junctions (MTJs) and spin valves, having one or more spin diffusion layers to diffuse the electron spins outside the MTJ or spin valve structure to reduce the spin transfer switching current for switching the free layer.
    Type: Grant
    Filed: December 23, 2005
    Date of Patent: September 30, 2008
    Assignee: Grandis Inc.
    Inventors: Yiming Huai, Zhitao Diao, Alex Panchula, Eugene Youjun Chen, Lien-Chang Wang
  • Patent number: 7369427
    Abstract: A method and system include providing a pinned layer, a free layer, and a spacer layer between the pinned and free layers. The spacer layer is nonmagnetic. The magnetic element is configured to allow the free layer to be switched due to spin transfer when a write current is passed through the magnetic element. In one aspect, the method and system include providing a spin engineered layer adjacent to the free layer. The spin engineered layer is configured to more strongly scatter majority electrons than minority electrons. In another aspect, at least one of the pinned, free, and spacer layers is a spin engineered layer having an internal spin engineered layer configured to more strongly scatter majority electrons than minority electrons. In this aspect, the magnetic element may include another pinned layer and a barrier layer between the free and pinned layers.
    Type: Grant
    Filed: September 9, 2004
    Date of Patent: May 6, 2008
    Assignee: Grandis, Inc.
    Inventors: Zhitao Diao, Yiming Huai, Thierry Valet, Paul P. Nguyen, Mahendra Pakala
  • Publication number: 20080061388
    Abstract: Devices having magnetic or magnetoresistive tunnel junctions (MTJS) have a multilayer insulator barrier layer to produce balanced write switching currents in the device circuitry, or to produce the magnetic devices with balanced critical spin currents required for spin torque transfer induced switching of the magnetization, or both for the MTJs under both the forward and reversed bias directions.
    Type: Application
    Filed: September 13, 2006
    Publication date: March 13, 2008
    Inventors: Zhitao Diao, Yiming Huai
  • Patent number: 7289356
    Abstract: A method and system for providing a magnetic memory is described. The method and system include providing a plurality of magnetic storage cells, a plurality of word lines, and a plurality of bit lines. Each of the plurality of magnetic storage cells includes a plurality of magnetic elements and at least one selection transistor. Each of the plurality of magnetic elements is capable of being programmed using spin transfer induced switching by a write current driven through the magnetic element. Each of the plurality of magnetic elements has a first end and a second end. The at least one selection transistor is coupled to the first end of each of the plurality of magnetic elements. The plurality of word lines is coupled with the plurality of selection transistors and selectively enables a portion of the plurality of selection transistors.
    Type: Grant
    Filed: June 8, 2005
    Date of Patent: October 30, 2007
    Assignee: Grandis, Inc.
    Inventors: Zhitao Diao, Yiming Huai, Mahendra Pakala, Zhenghong Qian
  • Publication number: 20070246787
    Abstract: Techniques and device designs associated with devices having magnetic or magnetoresistive tunnel junctions (MTJs) configured to operate based on spin torque transfer switching. On-plug MTJ designs and fabrication techniques are described.
    Type: Application
    Filed: March 29, 2006
    Publication date: October 25, 2007
    Inventors: Lien-Chang Wang, Eugene Chen, Yiming Huai, Zhitao Diao
  • Publication number: 20070171694
    Abstract: Magnetic multilayer structures, such as magnetic or magnetoresistive tunnel junctions (MTJs) and spin valves, having one or more spin diffusion layers to diffuse the electron spins outside the MTJ or spin valve structure to reduce the spin transfer switching current for switching the free layer.
    Type: Application
    Filed: December 23, 2005
    Publication date: July 26, 2007
    Inventors: Yiming Huai, Zhitao Diao, Alex Panchula, Eugene Chen, Lien-Chang Wang