Patents by Inventor Kunliang Zhang

Kunliang Zhang 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: 20140210022
    Abstract: The blocking temperature of the AFM layer in a TMR sensor has been raised by inserting a magnetic seed layer between the AFM layer and the bottom shield. This gives the device improved thermal stability, including improved SNR and BER.
    Type: Application
    Filed: January 25, 2013
    Publication date: July 31, 2014
    Applicant: Headway Technologies, Inc.
    Inventors: Junjie Quan, Kunliang Zhang, Min Li, Hui-Chuan Wang
  • Publication number: 20140183673
    Abstract: A TMR stack or a GMR stack, ultimately formed into a sensor or MRAM element, include insertion layers of Fe or iron rich layers of FeX in its ferromagnetic free layer and/or the AP1 layer of its SyAP pinned layer. X is a non-magnetic, metallic element (or elements) chosen from Ta, Hf, V, Co, Mo, Zr, Nb or Ti whose total atom percent is less than 50%. The insertion layers are between 1 and 10 angstroms in thickness, with between 2 and 5 angstroms being preferred and, in the TMR stack, they are inserted adjacent to the interfaces between a tunneling barrier layer and the ferromagnetic free layer or the tunneling barrier layer and the AP1 layer of the SyAP pinned layer in the TMR stack. The insertion layers constrain interdiffusion of B and Ni from CoFeB and NiFe layers and block NiFe crystalline growth.
    Type: Application
    Filed: January 2, 2013
    Publication date: July 3, 2014
    Applicant: HEADWAY TECHNOLOGIES, INC.
    Inventors: Kunliang Zhang, Hui-Chuan Wang, Junjie Quan, Yewhee Chye, Min Li
  • Patent number: 8747629
    Abstract: A TMR sensor with a free layer having a FL1/FL2/FL3 configuration is disclosed in which FL1 is FeCo or a FeCo alloy with a thickness between 2 and 15 Angstroms. The FL2 layer is made of CoFeB or a CoFeB alloy having a thickness from 2 to 10 Angstroms. The FL3 layer is from 10 to 100 Angstroms thick and has a negative ? to offset the positive ? from FL1 and FL2 layers and is comprised of CoB or a CoBQ alloy where Q is one of Ni, Mn, Tb, W, Hf, Zr, Nb, and Si. Alternatively, the FL3 layer may be a composite such as CoB/CoFe, (CoB/CoFe)n where n is ?2 or (CoB/CoFe)m/CoB where m is ?1. The free layer described herein affords a high TMR ratio above 60% while achieving low values for ? (<5×10?6), RA (1.5 ohm/?m2), and Hc (<6 Oe).
    Type: Grant
    Filed: September 22, 2008
    Date of Patent: June 10, 2014
    Assignee: Headway Technologies, Inc.
    Inventors: Hui-Chuan Wang, Tong Zhao, Min Li, Kunliang Zhang
  • Publication number: 20140138783
    Abstract: A magneto-resistive device having a large output signal as well as a high signal-to-noise ratio is described along with a process for forming it. This improved performance was accomplished by expanding the free layer into a multilayer laminate comprising at least three ferromagnetic layers separated from one another by antiparallel coupling layers. The ferromagnetic layer closest to the transition layer must include CoFeB while the furthermost layer is required to have low Hc as well as a low and negative lambda value. One possibility for the central ferromagnetic layer is NiFe but this is not mandatory.
    Type: Application
    Filed: January 28, 2014
    Publication date: May 22, 2014
    Applicant: Headway Technologies, Inc.
    Inventors: Tong Zhao, Hui-Chaun Wang, Yu-Chen Zhou, Min Li, Kunliang Zhang
  • Publication number: 20140106182
    Abstract: A sub-structure, suitable for use as a hot seed on which to form a perpendicular magnetic main write pole, is described. It is made up of a buffer layer of atomic layer deposited alumina on which there are one or more seed layers having a body-centered cubic (bcc) crystal structure. Finally, the high coercivity magnetic film lies on the seed layer(s). It is critical that the high coercivity magnetic film be deposited at a very low deposition rate (around 1 Angstrom per second).
    Type: Application
    Filed: October 14, 2012
    Publication date: April 17, 2014
    Applicant: HEADWAY TECHNOLOGIES, INC.
    Inventors: Shengyuan Wang, Kunliang Zhang, Min Li
  • Patent number: 8692343
    Abstract: The performance of an MR device has been improved by inserting one or more Magneto-Resistance Enhancing Layers (MRELs) into approximately the center of one or more of the active layers (such as AP1, SIL, FGL, and Free layers). An MREL is a layer of a low band gap, high electron mobility semiconductor such as ZnO or a semimetal such as Bi.
    Type: Grant
    Filed: April 26, 2010
    Date of Patent: April 8, 2014
    Assignee: Headway Technologies, Inc.
    Inventors: Kunliang Zhang, Min Li, Yuchen Zhou
  • Patent number: 8659292
    Abstract: A CPP MR sensor interposes a tapered soft magnetic flux guide (FG) layer between a hard magnetic biasing layer (HB) and the free layer of the sensor stack. The flux guide channels the flux of the hard magnetic biasing layer to effectively bias the free layer, while eliminating instability problems associated with magnetostatic coupling between the hard bias layers and the upper and lower shields surrounding the sensor when the reader-shield-spacing (RSS) is small.
    Type: Grant
    Filed: March 5, 2010
    Date of Patent: February 25, 2014
    Assignee: Headway Technologies, Inc.
    Inventors: Yuchen Zhou, Tong Zhao, Kunliang Zhang
  • Patent number: 8653615
    Abstract: A magneto-resistive device having a large output signal as well as a high signal-to-noise ratio is described along with a process for forming it. This improved performance was accomplished by expanding the free layer into a multilayer laminate comprising at least three ferromagnetic layers separated from one another by antiparallel coupling layers. The ferromagnetic layer closest to the transition layer must include CoFeB while the furthermost layer is required to have low Hc as well as a low and negative lambda value. One possibility for the central ferromagnetic layer is NiFe but this is not mandatory.
    Type: Grant
    Filed: November 19, 2008
    Date of Patent: February 18, 2014
    Assignee: Headway Technologies, Inc.
    Inventors: Tong Zhao, Hui-Chuan Wang, Yu-Chen Zhou, Min Li, Kunliang Zhang
  • Patent number: 8591751
    Abstract: High Hc (>4,000 Oe) and high Hk (>1 Tesla) has been achieved in FePt films as thin as 70 Angstroms. This was accomplished by starting with a relatively thick film having the required high coercivity, coating it with a suitable material such as Ta, and then using ion beam etching to remove surface material until the desired thickness was reached.
    Type: Grant
    Filed: September 30, 2011
    Date of Patent: November 26, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Kunliang Zhang, Min Zheng, Min Li
  • Publication number: 20130277780
    Abstract: A high performance TMR sensor is fabricated by employing a free layer with a trilayer configuration represented by FeCo/CoFeB/CoB, FeCo/CoB/CoFeB, FeCo/CoFe/CoB, or FeCo/FeB/CoB 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 included in a composite free layer or as a single free layer in the case of CoNiFeBM. A 15 to 30% in improvement in TMR ratio over a conventional CoFe/NiFe free layer is achieved while maintaining low Hc and RA<3 ohm-um2. In bilayer or trilayer embodiments, magnetostriction (?) between ?5×10?6 and 5×10?6 is achieved by combining CoB (??) and one or more layers having a positive ?.
    Type: Application
    Filed: June 24, 2013
    Publication date: October 24, 2013
    Inventors: Hui-Chuan Wang, Tong Zhao, Min Li, Kunliang Zhang
  • Patent number: 8563147
    Abstract: A hard bias (HB) structure for producing longitudinal bias to stabilize a free layer in an adjacent spin valve is disclosed and includes a composite seed layer made of at least Ta and a metal layer having a fcc(111) or hcp(001) texture to enhance perpendicular magnetic anisotropy (PMA) in an overlying (Co/Ni)X laminated layer. The (Co/Ni)X HB layer deposition involves low power and high Ar pressure to avoid damaging Co/Ni interfaces and thereby preserves PMA. A capping layer is formed on the HB layer to protect against etchants in subsequent process steps. After initialization, magnetization direction in the HB layer is perpendicular to the sidewalls of the spin valve and generates an Mrt value that is greater than from an equivalent thickness of CoPt. A non-magnetic metal separation layer may be formed on the capping layer and spin valve to provide an electrical connection between top and bottom shields.
    Type: Grant
    Filed: June 24, 2009
    Date of Patent: October 22, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Kunliang Zhang, Min Li, Yuchen Zhou, Min Zheng
  • Patent number: 8557407
    Abstract: A high performance TMR sensor is fabricated by incorporating a tunnel barrier having a Mg/MgO/Mg configuration. The 4 to 14 Angstroms thick lower Mg layer and 2 to 8 Angstroms thick upper Mg layer are deposited by a DC sputtering method while the MgO layer is formed by a NOX process involving oxygen pressure from 0.1 mTorr to 1 Torr for 15 to 300 seconds. NOX time and pressure may be varied to achieve a MR ratio of at least 34% and a RA value of 2.1 ohm-um2. The NOX process provides a more uniform MgO layer than sputtering methods. The second Mg layer is employed to prevent oxidation of an adjacent ferromagnetic layer. In a bottom spin valve configuration, a Ta/Ru seed layer, IrMn AFM layer, CoFe/Ru/CoFeB pinned layer, Mg/MgO/Mg barrier, CoFe/NiFe free layer, and a cap layer are sequentially formed on a bottom shield in a read head.
    Type: Grant
    Filed: August 6, 2010
    Date of Patent: October 15, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Tong Zhao, Kunliang Zhang, Hui Chuan Wang, Yu-Hsia Chen, Min Li
  • Patent number: 8542466
    Abstract: A magneto-resistance effect element, including a fixed magnetization layer of which a magnetization is substantially fixed in one direction, a free magnetization layer of which a magnetization is rotated in accordance with an external magnetic field and which is formed opposite to the fixed magnetization layer, a spacer layer including a current confining layer with an insulating layer and a conductor to pass a current through the insulating layer in a thickness direction thereof, a thin film layer, and a functional layer.
    Type: Grant
    Filed: January 14, 2013
    Date of Patent: September 24, 2013
    Assignees: Kabushiki Kaisha Toshiba, TDK Corporation
    Inventors: Yoshihiko Fuji, Hideaki Fukuzawa, Hiromi Yuasa, Kunliang Zhang, Min Li, Michiko Hara, Yoshinari Kurosaki
  • Patent number: 8493694
    Abstract: The free layer of a CPP-TMR sensor is biased by laterally disposed hard bias (HB) layers that include a seedlayer structure, a magnetic layer structure of high coercivity material and a capping layer structure. The magnetic layer structure is a layer of FePt-containing material, such as FePtCu, while the seedlayers and capping layers include layers of Cr, CrTi, Fe, FeCo or FeCoMo. These combinations enable the promotion of the L10 phase of the FePt-containing material which provides a high coercivity magnetic layer structure at much lower annealing temperatures than in the prior art.
    Type: Grant
    Filed: November 22, 2010
    Date of Patent: July 23, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Min Zheng, Kunliang Zhang, Min Li
  • Patent number: 8490279
    Abstract: A method of forming a hard bias (HB) structure for longitudinally biasing a free layer in a MR sensor is disclosed. A HB layer is formed with easy axis growth perpendicular to an underlying seed layer which is formed above a substrate and along two sidewalls of the sensor. In one embodiment, a conformal soft magnetic layer that may be a top shield is deposited on the HB layer to provide direct exchange coupling that compensates HB surface charges. Optionally, a thin capping layer on the HB layer enables magneto-static shield-HB coupling. After HB initialization, HB regions along the sensor sidewalls have magnetizations that are perpendicular to the sidewalls as a result of surface charges near the seed layer. Sidewalls may be extended into the substrate (bottom shield) to give enhanced protection against side reading.
    Type: Grant
    Filed: September 24, 2010
    Date of Patent: July 23, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Yuchen Zhou, Kenichi Takano, Kunliang Zhang
  • Patent number: 8488373
    Abstract: A spin transfer (torque) oscillator (STO) with a non-magnetic spacer formed between a spin injection layer (SIL) and a field generation layer (FGL), and with an interfacial layer comprised of Fe(100-V)CoV where v is from 5 to 100 atomic % formed between the SIL and non-magnetic spacer is disclosed. A composite seed layer made of Ta and a metal layer having a fcc(111) or hcp(001) texture is used to enhance perpendicular magnetic anisotropy (PMA) in the STO device. The interfacial layer quenches SIL oscillations and thereby stabilizes the SIL against FGL oscillations. The interfacial layer preferably has a thickness from 5 to 50 Angstroms and enhances amplitude (dR/R) in the STO device. The STO device may have a top SIL or bottom SIL configuration. The SIL is typically a laminated structure such as (Co/Ni)X where x is between 5 and 50.
    Type: Grant
    Filed: October 3, 2011
    Date of Patent: July 16, 2013
    Assignees: TDK Corporation, Kabushiki Kaisha Toshiba
    Inventors: Kunliang Zhang, Min Li, Yuchen Zhou, Soichi Oikawa, Hitoshi Iwasaki, Kenichiro Yamada, Katsuhiko Koui
  • Patent number: 8484830
    Abstract: A CPP-GMR spin valve having a CoFe/NiFe composite free layer is disclosed in which Fe content of the CoFe layer ranges from 20 to 70 atomic % and Ni content in the NiFe layer varies, from 85 to 100 atomic % to maintain low Hc and ?s values. A small positive magnetostriction value in a Co75Fe25 layer is used to offset a negative magnetostriction value in a Ni90Fe10layer. The CoFe layer is deposited on a sensor stack in which a seed layer, AFM layer, pinned layer, and non-magnetic spacer layer are sequentially formed on a substrate. After a NiFe layer and capping layer are sequentially deposited on the CoFe layer, the sensor stack is patterned to give a sensor element with top and bottom surfaces and a sidewall connecting the top and bottom surfaces. Thereafter, a dielectric layer is formed adjacent to the sidewalls.
    Type: Grant
    Filed: April 4, 2011
    Date of Patent: July 16, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Kunliang Zhang, Min Li, Yu-Hsia Chen, Chyu-Jiuh Torng
  • Patent number: 8477462
    Abstract: Plasma nitridation, in place of plasma oxidation, is used for the formation of a CCP layer. Al, Mg, Hf, etc. all form insulating nitrides under these conditions. Maintaining the structure at a temperature of at least 150° C. during plasma nitridation and/or performing post annealing at a temperature of 220° C. or higher, ensures that no copper nitride can form. Additionally, unintended oxidation by molecular oxygen of the exposed magnetic layers (mainly the pinned and free layers) is also avoided.
    Type: Grant
    Filed: December 2, 2012
    Date of Patent: July 2, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Kunliang Zhang, Min Li, Yue Liu
  • Patent number: 8472151
    Abstract: A high performance TMR sensor is fabricated by employing a free layer with a trilayer configurations represented by FeCo/CoFeB/CoB, FeCo/CoB/CoFeB, FeCo/CoFe/CoB, or FeCo/FeB/CoB 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 included in a composite free layer or as a single free layer in the case of CoNiFeBM. A 15 to 30% in improvement in TMR ratio over a conventional CoFe/NiFe free layer is achieved while maintaining low Hc and RA<3 ohm-um2. In bilayer or trilayer embodiments, magnetostriction (?) between ?5×10?6 and 5×10?6 is achieved by combining CoB (??) and one or more layers having a positive ?.
    Type: Grant
    Filed: April 11, 2012
    Date of Patent: June 25, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Hui-Chuan Wang, Tong Zhao, Min Li, Kunliang Zhang
  • Patent number: 8456781
    Abstract: A composite free layer having a FL1/insertion/FL2 configuration where a top surface of FL1 is treated with a weak plasma etch is disclosed for achieving enhanced dR/R while maintaining low RA, and low ? in TMR or GMR sensors. The weak plasma etch removes less than about 0.2 Angstroms of FL1 and is believed to modify surface structure and possibly increase surface energy. FL1 may be CoFe, CoFe/CoFeB, or alloys thereof having a (+) ? value. FL2 may be CoFe, NiFe, or alloys thereof having a (?) ? value. The thin insertion layer includes at least one magnetic element such as Co, Fe, and Ni, and at least one non-magnetic element. When CoFeBTa is selected as insertion layer, the CoFeB:Ta ratio is from 1:1 to 4:1.
    Type: Grant
    Filed: July 30, 2012
    Date of Patent: June 4, 2013
    Assignee: Headway Technologies, Inc.
    Inventors: Tong Zhao, Hui-Chuan Wang, Min Li, Kunliang Zhang