Patents by Inventor Tong Zhao

Tong Zhao 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: 20090165288
    Abstract: A high performance TMR element is fabricated by inserting an oxygen surfactant layer (OSL) between a pinned layer and AlOx tunnel barrier layer in a bottom spin valve configuration. The pinned layer preferably has a SyAP configuration with an outer pinned layer, a Ru coupling layer, and an inner pinned layer comprised of CoFeXBY/CoFeZ wherein x=0 to 70 atomic %, y=0 to 30 atomic %, and z=0 to 100 atomic %. The OSL is formed by treating the CoFeZ layer with oxygen plasma. The AlOx tunnel barrier has improved uniformity of about 2% across a 6 inch wafer and can be formed from an Al layer as thin as 5 Angstroms. As a result, the Hin value can be decreased by ? to about 32 Oe. A dR/R of 25% and a RA of 3 ohm-cm2 have been achieved for TMR read head applications.
    Type: Application
    Filed: January 27, 2009
    Publication date: July 2, 2009
    Inventors: Hui-Chuan Wang, Tong Zhao, Min Li, Kunliang Zhang
  • Publication number: 20090161266
    Abstract: A high performance TMR element is fabricated by inserting an oxygen surfactant layer (OSL) between a pinned layer and AlOx tunnel barrier layer in a bottom spin valve configuration. The pinned layer preferably has a SyAP configuration with an outer pinned layer, a Ru coupling layer, and an inner pinned layer comprised of CoFeXBY/CoFeZ wherein x=0 to 70 atomic %, y=0 to 30 atomic %, and z=0 to 100 atomic %. The OSL is formed by treating the CoFeZ layer with oxygen plasma. The AlOx tunnel barrier has improved uniformity of about 2% across a 6 inch wafer and can be formed from an Al layer as thin as 5 Angstroms. As a result, the Hin value can be decreased by ? to about 32 Oe. A dR/R of 25% and a RA of 3 ohm-cm2 have been achieved for TMR read head applications.
    Type: Application
    Filed: January 27, 2009
    Publication date: June 25, 2009
    Inventors: Hui-Chuan Wang, Tong Zhao, Min Li, Kunliang Zhang
  • Publication number: 20090160097
    Abstract: A single annealing process simultaneously creates local areas of ferroelectric imprint that can be used as markers, and areas with low leakage current that exhibit ideal symmetric switching on ferroelectric recording media.
    Type: Application
    Filed: December 20, 2007
    Publication date: June 25, 2009
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Tong Zhao, Andreas Roelofs, Cedric Stephane Bedoya
  • Patent number: 7538987
    Abstract: A CPP spin-valve element formed on a substrate including a free layer structure including at least one ferromagnetic layer and a pinned layer structure including at least one ferromagnetic layer. The free layer is magnetically softer than the pinned layer. A thin non-magnetic spacer layer structure configured to separate the free layer and the pinned layer is provided in order to prevent a magnetic coupling between the free and pinned layer structures, and to allow an electric current to go there through. At least two current-confining (CC) layer structures including at least two parts having significantly different current conductivities are incorporated therein.
    Type: Grant
    Filed: July 3, 2003
    Date of Patent: May 26, 2009
    Assignees: University of Alabama, Fujitsu, Ltd.
    Inventors: Hideo Fujiwara, Keiichi Nagasaka, Tong Zhao, William H. Butler, Julian Velev, Amrit Bandyopadhyay
  • Publication number: 20090121710
    Abstract: A TMR sensor and a CPP GMR sensor all include a free layer that is of the form CoFexBy/non-magnetic layer/NiFez or of the form CoFe/CoFeB/non-magnetic layer/NiFe, where, in one embodiment, the thickness of the non-magnetic layer is less than approximately 15 angstroms and the atom percentage x, z of Fe can vary between 0 and 70% for x and 0 and 100% for z and the atom percentage, y, of B can vary between 0 and 30%. This arrangement can produce a 5-10% improvement in dR/R and can allow the coupling field between the CoFeB and the NiFe to be strong enough that an in-stack biasing of the CoFeB layer occurs and the hysteresis behavior and stability of the sensor is improved.
    Type: Application
    Filed: November 9, 2007
    Publication date: May 14, 2009
    Inventors: Hui-Chuan Wang, Tong Zhao, Kunliang Zhang, Min Li
  • Publication number: 20090122450
    Abstract: A high performance TMR sensor is fabricated by employing a free layer comprised of CoBX with a ? between ?5×10?6 and 0 on a MgOX tunnel barrier. Optionally, a FeCo/CoBX free layer configuration may be used where x is about 1 to 30 atomic %. Trilayer configurations represented by FeCo/CoFeB/CoBX, FeCo/CoBX/CoFeB, FeCoY/CoFeW/CoBX, or FeCoY/FeB/CoBX may also be employed. Alternatively, CoNiFeB or CoNiFeBM formed by co-sputtering CoB with CoNiFe or CoNiFeM, respectively, where M is V, Ti, Zr, Nb, Hf, Ta, or Mo may be substituted for CoBx in the aforementioned embodiments. A 15 to 30% in improvement in TMR ratio over a conventional CoFe/NiFe free layer is achieved while maintaining a low Hc and RA<3 ohm-um2. In bilayer or trilayer embodiments, ? between ?5×10?6 and 5×10?6 is achieved by combining CoBx (??) and one or more layers having a positive ?.
    Type: Application
    Filed: November 8, 2007
    Publication date: May 14, 2009
    Inventors: Hui-Chuan Wang, Tong Zhao, Min Li, Kunliang Zhang
  • Patent number: 7528457
    Abstract: An MTJ in an MRAM array or TMR read head is disclosed in which a capping layer has a bilayer configuration with a non-magnetic NiFeX inner layer on a NiFe free layer and a Ta layer on the NiFeX layer to improve dR/R and minimize magnetostriction. Optionally, a trilayer configuration may be employed where the Ta layer is sandwiched between an inner NiFeX layer and an outer Ru layer. The X component in NiFeX is preferably an element having an oxidation potential greater than Ni or Fe such as Mg, Hf, Zr, Nb, or Ta. NiFeX is preferably formed by co-sputtering a NiFe target with an X target at a forward power of about 200 W and 50 W, respectively. In an MRAM structure, the Mg content in NiFeMg may be increased to >50 atomic % to improve the gettering power of removing oxygen from the free layer.
    Type: Grant
    Filed: April 14, 2006
    Date of Patent: May 5, 2009
    Assignee: MagIC Technologies, Inc.
    Inventors: Cheng T. Horng, Hui-Chuan Wang, Min Li, Ru-Ying Tong, Tong Zhao, Yimin Guo
  • Publication number: 20090092805
    Abstract: An apparatus includes a ferroelectric layer and a polarization pattern configured in the ferroelectric layer to represent position data. The polarization pattern has a switchable polarization state domain and an unswitchable polarization state domain. A method includes providing a ferroelectric layer and establishing a polarization pattern in the ferroelectric layer to represent position data.
    Type: Application
    Filed: October 3, 2007
    Publication date: April 9, 2009
    Applicant: Seagate Technology LLC
    Inventors: Tong Zhao, Andreas Karl Roelofs, Florin Zavaliche, Philip George Pitcher
  • Publication number: 20090086615
    Abstract: A ferroelectric polarization pattern with differing feedback signals. An apparatus including a ferroelectric layer and a polarization pattern configured in the ferroelectric layer to represent position data. The polarization pattern has a first switchable polarization state domain and a second switchable polarization state domain that are both switchable by an applied signal. The first switchable polarization state domain has a first feedback signal in response to the applied signal that is different than a second feedback signal of the second switchable polarization state domain at the applied signal.
    Type: Application
    Filed: October 2, 2007
    Publication date: April 2, 2009
    Applicant: Seagate Technology LLC
    Inventors: Florin Zavaliche, Philip George Pitcher, Tong Zhao, Dierk Guenter Bolten
  • Publication number: 20090086613
    Abstract: An apparatus that provides for non-destructive readback of a ferroelectric material. The apparatus can include a ferroelectric layer with a scannable surface wherein the ferroelectric layer has a compensation charge adjacent the scannable surface. The apparatus also can include an electrode adjacent the scannable surface to sense the compensation charge. A related method is also disclosed.
    Type: Application
    Filed: October 2, 2007
    Publication date: April 2, 2009
    Applicant: Seagate Technology LLC
    Inventors: Tong Zhao, Martin G. Forrester, Florin Zavaliche, Dierk Guenter Bolten, Andreas Karl Roelofs
  • Patent number: 7497007
    Abstract: A high performance TMR element is fabricated by inserting an oxygen surfactant layer (OSL) between a pinned layer and AlOx tunnel barrier layer in a bottom spin valve configuration. The pinned layer preferably has a SyAP configuration with an outer pinned layer, a Ru coupling layer, and an inner pinned layer comprised of CoFeXBY/CoFeZ wherein x=0 to 70 atomic %, y=0 to 30 atomic %, and z=0 to 100 atomic %. The OSL is formed by treating the CoFez layer with oxygen plasma. The AlOx tunnel barrier has improved uniformity of about 2% across a 6 inch wafer and can be formed from an Al layer as thin as 5 Angstroms. As a result, the Hin value can be decreased by ? to about 32 Oe. A dR/R of 25% and a RA of 3 ohm-cm2 have been achieved for TMR read head applications.
    Type: Grant
    Filed: July 14, 2005
    Date of Patent: March 3, 2009
    Assignee: Headway Technologies, Inc.
    Inventors: Hui-Chuan Wang, Tong Zhao, Min Li, Kunliang Zhang
  • Patent number: 7476954
    Abstract: A MTJ structure is disclosed in which the seed layer is made of a lower Ta layer, a middle Hf layer, and an upper NiFe or NiFeX layer where X is Co, Cr, or Cu. Optionally, Zr, Cr, HfZr, or HfCr may be employed as the middle layer and materials having FCC structures such as CoFe and Cu may be used as the upper layer. As a result, the overlying layers in a TMR sensor will be smoother and less pin dispersion is observed. The Hex/Hc ratio is increased relative to that for a MTJ having a conventional Ta/Ru seed layer configuration. The trilayer seed configuration is especially effective when an IrMn AFM layer is grown thereon and thereby reduces Hin between the overlying pinned layer and free layer. Ni content in the NiFe or NiFeX middle layer is above 30 atomic % and preferably >80 atomic %.
    Type: Grant
    Filed: January 12, 2007
    Date of Patent: January 13, 2009
    Assignee: Headway Technologies, Inc.
    Inventors: Hui-Chuan Wang, Kunliang Zhang, Tong Zhao, Min Li
  • Publication number: 20080316657
    Abstract: An insertion layer is provided between an AFM layer and an AP2 pinned layer in a GMR or TMR element to improve exchange coupling properties by increasing Hex and the Hex/Hc ratio without degrading the MR ratio. The insertion layer may be a 1 to 15 Angstrom thick amorphous magnetic layer comprised of at least one element of Co, Fe, or Ni, and at least one element having an amorphous character selected from B, Zr, Hf, Nb, Ta, Si, or P, or a 1 to 5 Angstrom thick non-magnetic layer comprised of Cu, Ru, Mn, Hf, or Cr. Preferably, the content of the one or more amorphous elements in the amorphous magnetic layer is less than 40 atomic %. Optionally, the insertion layer may be formed within the AP2 pinned layer. Examples of an insertion layer are CoFeB, CoFeZr, CoFeNb, CoFeHf, CoFeNiZr, CoFeNiHf, and CoFeNiNbZr.
    Type: Application
    Filed: June 19, 2007
    Publication date: December 25, 2008
    Inventors: Kunliang Zhang, Hui-Chuan Wang, Tong Zhao, Min Li
  • Publication number: 20080299679
    Abstract: A high performance TMR sensor is fabricated by employing a composite inner pinned (AP1) layer in an AP2/Ru/AP1 pinned layer configuration. In one embodiment, there is a 10 to 80 Angstrom thick lower CoFeB or CoFeB alloy layer on the Ru coupling layer, a and 5 to 50 Angstrom thick Fe or Fe alloy layer on the CoFeB or CoFeB alloy, and a 5 to 30 Angstrom thick Co or Co rich alloy layer formed on the Fe or Fe alloy. A MR ratio of about 48% with a RA of <2 ohm-um2 is achieved when a CoFe AP2 layer, MgO (NOX) tunnel barrier, and CoFe/NiFe free layer are used in the TMR stack. Improved RA uniformity and less head noise are observed. Optionally, a CoFe layer may be inserted between the coupling layer and CoFeB or CoFeB alloy layer to improve pinning strength and enhance crystallization.
    Type: Application
    Filed: May 29, 2007
    Publication date: December 4, 2008
    Inventors: Tong Zhao, Hui-Chuan Wang, Kunliang Zhang, Yu-Hsia Chen, Min Li
  • Publication number: 20080260943
    Abstract: The conventional free layer in a CPP GMR or TMR read head has been replaced by a tri-layer laminate comprising Co rich CoFe, moderately Fe rich NiFe, and heavily Fe rich NiFe. The result is an improved device that has a higher MR ratio than prior art devices, while still maintaining free layer softness and acceptable magnetostriction. A process for manufacturing the device is described.
    Type: Application
    Filed: June 19, 2008
    Publication date: October 23, 2008
    Inventors: Hui-Chuan Wang, Min Li, Tong Zhao, Kunliang Zhang, Chyu-Jiuh Torng
  • Publication number: 20080246103
    Abstract: The dR/R ratios of TMR and GMR devices, having a FeCo/NiFe type of free layer, have been significantly increased by inserting a suitable surfactant layer within (as opposed to above or below) the free layer. Our preferred surfactant material has been oxygen but similar-acting materials could be substituted. The concept can be applied to GMR CPP, CIP, and CCP sensor designs.
    Type: Application
    Filed: April 5, 2007
    Publication date: October 9, 2008
    Inventors: Hui-Chuan Wang, Tong Zhao, Min Li, Kunliang Zhang
  • Patent number: 7431961
    Abstract: In this invention, we replace low resistivity NiFe with high-resistivity FeNi for the FL2 portion of a composite free layer in a CIP GMR sensor in order to minimize current shunting effects while still retaining both magnetic softness and low magnetostriction. A process for manufacturing the device is also described.
    Type: Grant
    Filed: December 10, 2004
    Date of Patent: October 7, 2008
    Assignee: Headway Technologies, Inc.
    Inventors: Tong Zhao, Hui-Chuan Wang, Yun-Fei Li, Chyu-Jiuh Torng
  • Publication number: 20080219042
    Abstract: By inserting a spin polarizing layer (typically pure iron) within the free layer of a MTJ or GMR memory cell, dR/R can be improved without significantly affecting other free layer properties such as Hc. Additional performance improvements can be achieved by also inserting a surfactant layer (typically oxygen) within the free layer.
    Type: Application
    Filed: March 7, 2007
    Publication date: September 11, 2008
    Inventors: Hui-Chuan Wang, Tong Zhao, Kunliang Zhang, Min Li
  • Publication number: 20080212243
    Abstract: A TMR read head with improved voltage breakdown is formed by laying down the AP1 layer as two or more layers. Each AP1 sub-layer is exposed to a low energy plasma for a short time before the next layer is deposited. This results in a smooth surface, onto which to deposit the tunneling barrier layer, with no disruption of the surface crystal structure of the completed AP1 layer.
    Type: Application
    Filed: May 12, 2008
    Publication date: September 4, 2008
    Inventors: Tong Zhao, Chyu-Jiuh Torng, Hui-Chuan Wang
  • Publication number: 20080209714
    Abstract: A TMR read head with improved voltage breakdown is formed by laying down the AP1 layer as two or more layers. Each AP1 sub-layer is exposed to a low energy plasma for a short time before the next layer is deposited. This results in a smooth surface, onto which to deposit the tunneling barrier layer, with no disruption of the surface crystal structure of the completed AP1 layer.
    Type: Application
    Filed: May 12, 2008
    Publication date: September 4, 2008
    Inventors: Tong Zhao, Chyu-Jiuh Torng, Hui-Chuan Wang