Patents by Inventor Jijun Sun

Jijun Sun 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: 7226796
    Abstract: A magnetic tunnel junction (MTJ), which is useful in magnetoresistive random access memories (MRAMs), has a free layer which is a synthetic antiferromagnet (SAF) structure. This SAF is composed of two ferromagnetic layers that are separated by a coupling layer. The coupling layer has a base material that is non-magnetic and also other materials that improve thermal endurance, control of the coupling strength of the SAF, and magnetoresistance ratio (MR). The preferred base material is ruthenium and the preferred other material is tantalum. Furthering these benefits, cobalt-iron is added at the interface between the tantalum and one of the ferromagnetic layers. Also the coupling layer can have even more layers and the materials used can vary. Also the coupling layer itself can be an alloy.
    Type: Grant
    Filed: July 15, 2005
    Date of Patent: June 5, 2007
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Srinivas V. Pietambaram, Renu W. Dave, Jon M. Slaughter, Jijun Sun
  • Publication number: 20070037299
    Abstract: Low power magnetoresistive random access memory elements and methods for fabricating the same are provided. In one embodiment, a magnetoresistive random access device has an array of memory elements. Each element comprises a fixed magnetic portion, a tunnel barrier portion, and a free SAF structure. The array has a finite magnetic field programming window Hwin represented by the equation Hwin?(Hsat??sat)?(Hsw+?sw), where Hsw is a mean switching field for the array, Hsat is a mean saturation field for the array, and Hsw for each memory element is represented by the equation HSW??{square root over (HkHSAT)}, where Hk represents a total anisotropy and HSAT represents an anti-ferromagnetic coupling saturation field for the free SAF structure of each memory element. N is an integer greater than or equal to 1. Hk, HSAT, and N for each memory element are selected such that the array requires current to operate that is below a predetermined current value.
    Type: Application
    Filed: October 16, 2006
    Publication date: February 15, 2007
    Inventors: Nicholas Rizzo, Renu Dave, Bradley Engel, Jason Janesky, JiJun Sun
  • Patent number: 7129098
    Abstract: Low power magnetoresistive random access memory elements and methods for fabricating the same are provided. In one embodiment, a magnetoresistive random access device has an array of memory elements. Each element comprises a fixed magnetic portion, a tunnel barrier portion, and a free SAF structure. The array has a finite magnetic field programming window Hwin represented by the equation Hwin?(Hsat?N?sat)?(Hsw+N?sw), where Hsw is a mean switching field for the array, Hsat is a mean saturation field for the array, and Hsw for each memory element is represented by the equation HSW??{square root over (HkHSAT)}, where Hk represents a total anisotropy and HSAT represents an anti-ferromagnetic coupling saturation field for the free SAF structure of each memory element. N is an integer greater than or equal to 1. Hk, HSAT, and N for each memory element are selected such that the array requires current to operate that is below a predetermined current value.
    Type: Grant
    Filed: November 24, 2004
    Date of Patent: October 31, 2006
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Nicholas D. Rizzo, Renu W. Dave, Bradley N. Engel, Jason A. Janesky, JiJun Sun
  • Patent number: 7098495
    Abstract: Magnetic tunnel junction (“MTJ”) element structures and methods for fabricating MTJ element structures are provided. An MTJ element structure may comprise a crystalline pinned layer, an amorphous fixed layer, and a coupling layer disposed between the crystalline pinned layer and the amorphous fixed layer. The amorphous fixed layer is antiferromagnetically coupled to the crystalline pinned layer. The MTJ element further comprises a free layer and a tunnel barrier layer disposed between the amorphous fixed layer and the free layer. Another MTJ element structure may comprise a pinned layer, a fixed layer and a non-magnetic coupling layer disposed therebetween. A tunnel barrier layer is disposed between the fixed layer and a free layer. An interface layer is disposed adjacent the tunnel barrier layer and a layer of amorphous material. The first interface layer comprises a material having a spin polarization that is higher than that of the amorphous material.
    Type: Grant
    Filed: July 26, 2004
    Date of Patent: August 29, 2006
    Assignee: Freescale Semiconducor, Inc.
    Inventors: JiJun Sun, Renu W. Dave, Jon M. Slaughter, Johan Akerman
  • Publication number: 20060108620
    Abstract: Low power magnetoresistive random access memory elements and methods for fabricating the same are provided. In one embodiment, a magnetoresistive random access device has an array of memory elements. Each element comprises a fixed magnetic portion, a tunnel barrier portion, and a free SAF structure. The array has a finite magnetic field programming window Hwin represented by the equation Hwin?(Hsat?N?sat)?(Hsw+N?sw), where Hsw is a mean switching field for the array, Hsat is a mean saturation field for the array, and Hsw for each memory element is represented by the equation HSW??{square root over (HkHSAT)}, where Hk represents a total anisotropy and HSAT represents an anti-ferromagnetic coupling saturation field for the free SAF structure of each memory element. N is an integer greater than or equal to 1. Hk, HSAT, and N for each memory element are selected such that the array requires current to operate that is below a predetermined current value.
    Type: Application
    Filed: November 24, 2004
    Publication date: May 25, 2006
    Inventors: Nicholas Rizzo, Renu Dave, Bradley Engel, Jason Janesky, JiJun Sun
  • Publication number: 20060017081
    Abstract: Magnetic tunnel junction (“MTJ”) element structures and methods for fabricating MTJ element structures are provided. An MTJ element structure may comprise a crystalline pinned layer, an amorphous fixed layer, and a coupling layer disposed between the crystalline pinned layer and the amorphous fixed layer. The amorphous fixed layer is antiferromagnetically coupled to the crystalline pinned layer. The MTJ element further comprises a free layer and a tunnel barrier layer disposed between the amorphous fixed layer and the free layer. Another MTJ element structure may comprise a pinned layer, a fixed layer and a non-magnetic coupling layer disposed therebetween. A tunnel barrier layer is disposed between the fixed layer and a free layer. An interface layer is disposed adjacent the tunnel barrier layer and a layer of amorphous material. The first interface layer comprises a material having a spin polarization that is higher than that of the amorphous material.
    Type: Application
    Filed: July 26, 2004
    Publication date: January 26, 2006
    Inventors: JiJun Sun, Renu Dave, Jon Slaughter, Johan Akerman
  • Publication number: 20050247964
    Abstract: A magnetic tunnel junction (MTJ), which is useful in magnetoresistive random access memories (MRAMs), has a free layer which is a synthetic antiferromagnet (SAF) structure. This SAF is composed of two ferromagnetic layers that are separated by a coupling layer. The coupling layer has a base material that is non-magnetic and also other materials that improve thermal endurance, control of the coupling strength of the SAF, and magnetoresistance ratio (MR). The preferred base material is ruthenium and the preferred other material is tantalum. Furthering these benefits, cobalt-iron is added at the interface between the tantalum and one of the ferromagnetic layers. Also the coupling layer can have even more layers and the materials used can vary. Also the coupling layer itself can be an alloy.
    Type: Application
    Filed: July 15, 2005
    Publication date: November 10, 2005
    Inventors: Srinivas Pietambaram, Renu Dave, Jon Slaughter, Jijun Sun
  • Patent number: 6946697
    Abstract: A magnetic tunnel junction (MTJ), which is useful in magnetoresistive random access memories (MRAMs), has a free layer which is a synthetic antiferromagnet (SAF) structure. This SAF is composed of two ferromagnetic layers that are separated by a coupling layer. The coupling layer has a base material that is non-magnetic and also other materials that improve thermal endurance, control of the coupling strength of the SAF, and magnetoresistance ratio (MR). The preferred base material is ruthenium and the preferred other material is tantalum. Furthering these benefits, cobalt-iron is added at the interface between the tantalum and one of the ferromagnetic layers. Also the coupling layer can have even more layers and the materials used can vary. Also the coupling layer itself can be an alloy.
    Type: Grant
    Filed: December 18, 2003
    Date of Patent: September 20, 2005
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Srinivas V. Pietambaram, Renu W. Dave, Jon M. Slaughter, Jijun Sun
  • Publication number: 20050133840
    Abstract: A magnetic tunnel junction (MTJ), which is useful in magnetoresistive random access memories (MRAMs), has a free layer which is a synthetic antiferromagnet (SAF) structure. This SAF is composed of two ferromagnetic layers that are separated by a coupling layer. The coupling layer has a base material that is non-magnetic and also other materials that improve thermal endurance, control of the coupling strength of the SAF, and magnetoresistance ratio (MR). The preferred base material is ruthenium and the preferred other material is tantalum. Furthering these benefits, cobalt-iron is added at the interface between the tantalum and one of the ferromagnetic layers. Also the coupling layer can have even more layers and the materials used can vary. Also the coupling layer itself can be an alloy.
    Type: Application
    Filed: December 18, 2003
    Publication date: June 23, 2005
    Inventors: Srinivas Pietambaram, Renu Dave, Jon Slaughter, Jijun Sun
  • Patent number: 6818961
    Abstract: A method of fabricating a magnetoresistive tunneling junction cell comprising the steps of providing a substrate with a surface, depositing a first magnetic region (17) having a resultant magnetic moment vector onto the substrate, depositing an electrically insulating material (16) onto the first magnetic region, and depositing a second magnetic region (15) onto the electrically insulating material, wherein at least a portion of one of the first and second magnetic regions is formed by depositing said region at a nonzero deposition angle relative to a direction perpendicular to the surface of the substrate to create an induced anisotropy.
    Type: Grant
    Filed: June 30, 2003
    Date of Patent: November 16, 2004
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Nicholas D. Rizzo, Bradley N. Engel, Jason A. Janesky, Jon M. Slaughter, Jijun Sun
  • Patent number: 6801415
    Abstract: An improved and novel device and fabrication method for a magnetic element, and more particularly a magnetic element with a crystallographically disordered seed layer and/or template layer seeding the nanocrystalline growth of subsequent layers, including a pinning layer, a pinned layer, and fixed layer.
    Type: Grant
    Filed: August 30, 2002
    Date of Patent: October 5, 2004
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Jon M. Slaughter, Renu W. Dave, Jijun Sun
  • Patent number: 6710987
    Abstract: A magnetic tunnel junction device and method for making same is provided. A first ferromagnetic portion is provided. A barrier is provided on the first ferromagnetic portion. The barrier includes a first barrier portion on the first ferromagnetic portion. The first barrier portion is oxidized. After oxidizing, a second barrier portion is provided on the first barrier portion. The second barrier may be oxidized or annealed. A second ferromagnetic portion is provided on the barrier. The barrier of the resultant device has a reduced number of pinholes, minimizing the amount of the non-tunnel current, and an improved symmetry of electrical properties. This leads to advantages in performance characteristics and mass-production of the device.
    Type: Grant
    Filed: July 13, 2001
    Date of Patent: March 23, 2004
    Assignee: TDK Corporation
    Inventors: Jijun Sun, Satoru Araki
  • Publication number: 20040042128
    Abstract: An improved and novel device and fabrication method for a magnetic element, and more particularly a magnetic element with a crystallographically disordered seed layer and/or template layer seeding the nanocrystalline growth of subsequent layers, including a pinning layer, a pinned layer, and fixed layer.
    Type: Application
    Filed: August 30, 2002
    Publication date: March 4, 2004
    Inventors: Jon M. Slaughter, Renu W. Dave, Jijun Sun
  • Patent number: 6574079
    Abstract: A magnetic tunnel junction is made up of two ferromagnetic layers, one of which has its magnetic moment fixed and the other of which has its magnetic moment free to rotate, an insulating tunneling barrier layer between the ferromagnetic layers for permitting tunneling current perpendicularly through the layers. The insulating barrier is preferably formed by the oxidation of a thin metallic alloy layer of particular materials which lead to a nonmagnetic barrier having a relatively low barrier height. These low barrier height insulating materials allow for the formation of a magnetic tunnel junction with a relatively thick barrier while maintaining a low resistance that is suitable, for example, in magnetoresistance read head applications.
    Type: Grant
    Filed: July 13, 2001
    Date of Patent: June 3, 2003
    Assignee: TDK Corporation
    Inventors: Jijun Sun, Satoru Araki
  • Publication number: 20020097534
    Abstract: A magnetic tunnel junction device and method for making same is provided. A first ferromagnetic portion is provided. A barrier is provided on the first ferromagnetic portion. The barrier includes a first barrier portion on the first ferromagnetic portion. The first barrier portion is oxidized. After oxidizing, a second barrier portion is provided on the first barrier portion. The second barrier may be oxidized or annealed. A second ferromagnetic portion is provided on the barrier. The barrier of the resultant device has a reduced number of pinholes, minimizing the amount of the non-tunnel current, and an improved symmetry of electrical properties. This leads to advantages in performance characteristics and mass-production of the device.
    Type: Application
    Filed: July 13, 2001
    Publication date: July 25, 2002
    Applicant: TDK Corporation
    Inventors: Jijun Sun, Satoru Araki
  • Publication number: 20020054462
    Abstract: A magnetic tunnel junction is made up of two ferromagnetic layers, one of which has its magnetic moment fixed and the other of which has its magnetic moment free to rotate, an insulating tunneling barrier layer between the ferromagnetic layers for permitting tunneling current perpendicularly through the layers. The insulating barrier is preferably formed by the oxidation of a thin metallic alloy layer of particular materials which lead to a nonmagnetic barrier having a relatively low barrier height. These low barrier height insulating materials allow for the formation of a magnetic tunnel junction with a relatively thick barrier while maintaining a low resistance that is suitable, for example, in magnetoresistance read head applications.
    Type: Application
    Filed: July 13, 2001
    Publication date: May 9, 2002
    Applicant: TDK Corporation
    Inventors: Jijun Sun, Satoru Araki